diff --git a/content/Biokemi/Cellulära processer/.DS_Store b/content/Biokemi/Cellulära processer/.DS_Store index d4d518f..c8e5c92 100644 Binary files a/content/Biokemi/Cellulära processer/.DS_Store and b/content/Biokemi/Cellulära processer/.DS_Store differ diff --git a/content/Biokemi/Cellulära processer/Translation/Anteckningar.md b/content/Biokemi/Cellulära processer/Translation/Anteckningar.md index 39078cd..cab6e5c 100644 --- a/content/Biokemi/Cellulära processer/Translation/Anteckningar.md +++ b/content/Biokemi/Cellulära processer/Translation/Anteckningar.md @@ -4,4 +4,6 @@ tags: - translation - anteckningar föreläsare: Ana Luis +url: https://www.youtube.com/watch?v=gjjp-NUaCXE +date: 2024-11-25 --- diff --git a/content/Biokemi/Cellulära processer/Translation/2025_Protein synthesis Questions.pdf b/content/Biokemi/Cellulära processer/Translation/Instuderingsfrågor.pdf.pdf similarity index 100% rename from content/Biokemi/Cellulära processer/Translation/2025_Protein synthesis Questions.pdf rename to content/Biokemi/Cellulära processer/Translation/Instuderingsfrågor.pdf.pdf diff --git a/content/Biokemi/Cellulära processer/Translation/Lärandemål.md b/content/Biokemi/Cellulära processer/Translation/Lärandemål.md new file mode 100644 index 0000000..51f8541 --- /dev/null +++ b/content/Biokemi/Cellulära processer/Translation/Lärandemål.md @@ -0,0 +1,7 @@ +- tRNA stuktur och funktion. +- Aminoacylering av tRNA. +- Ribosomens struktur och funktion. +- Mekanismen för proteinsyntes (initiering, elongering, translokation och terminering). +- Regleringsmekanismer för proteinsyntesen + +Beskriva överföringen av genetisk information från mRNA till protein. \ No newline at end of file diff --git a/content/Biokemi/Cellulära processer/Translation/Slides.md b/content/Biokemi/Cellulära processer/Translation/Slides.md new file mode 100644 index 0000000..0fb572f --- /dev/null +++ b/content/Biokemi/Cellulära processer/Translation/Slides.md @@ -0,0 +1,561 @@ + +Chapter 8 and Chapter 20 +Ana Luis +ana.luis@medkem.gu.se +2025/04/28 + +--- + +Protein Biosynthesis + +(Translation) +Chapter 8 and Chapter 20 +Ana Luis +ana.luis@medkem.gu.se +2025/04/28 + +---- + +Learning goals + +• Explain how nucleic acid information is translated into an amino acid sequence and define the role of aminoacyl tRNA synthetases in this process + • Protein biosynthesis requires the translation of nucleotide sequences into amino acid sequences + • Describe features of the genetic code + • tRNA structure and function + • Aminoacyl-tRNA synthetases establish the genetic code + +• Define the role of ribosomes in protein synthesis + • Structure and function of ribosomes + • Mechanism of protein synthesis (initiation, elongation, translocation and termination) + +• Describe how certain chemicals can inhibit protein synthesis + • Antibiotics and toxins inhibit protein synthesis + +---- + +Why is important to understand the translation mechanisms? +![[Pasted image 20251125093128.png]] +### TRANSLATION + +#### Inhibition of translation of specific mRNAs can lead to diseasess +- Fragile X mental retardation syndrome: +- absence of the set of protein isoforms, derived from + alternative splicing of the Fragile X mental retardation + gene 1 (FMR1) + +#### Bacterial toxins can block of protein biosynthesis protein biosynthesis +- Diphtheria toxin + +#### Several antibiotics are inhibitors +- Streptomycin +- Tetracycline +- ….. + +⸻ + +Translation = the process of protein biosynthesis + +Adenine (A) +Cytosine (C) +Guanine (G) +Uracil (U) +Nucleic acid + +→ + +Amino acids +(A) Alanine +(R) Arginine +(N) Asparagine +(D) Aspartic acid +(C) Cysteine +(E) Glutamic acid +(Q) Glutamine +(G) Glycine +(H) Histidine +(I) Isoleucine +(L) Leucine +(K) Lysine +(M) Methionine +(F) Phenylalanine +(P) Proline +(S) Serine +(T) Threonine +(W) Tryptophan +(Y) Tyrosine +(V) Valine + +----- + +Translation = the process of protein biosynthesis + +The basics of protein biosynthesis are the same across all kingdoms of life: +• mRNA is decoded in the 5′-to-3′ direction one codon at a time +• the protein is synthesized in the amino-to-carboxyl direction +mRNA +A U G G U G G C U A A G C G G U G A +Methionine Valine Alanine Lisine Arginine Stop +5’ 3’ +Amino group +Carboxyl group +Amino group +Carboxyl + +⸻ + +tRNA + +a.a. +Translation = the process of protein biosynthesis +• anticodon - portion of the tRNA that base pairs with the codon +C G I +3’ 5’ +G C C +5’ 3’ +Codon +• codon - three coding bases on the mRNA template +• transfer RNA (tRNA) - function as adaptor molecules between a codon and +an amino acid (a.a.) +Anticodon +mRNA +The basics of protein biosynthesis are the same across all kingdoms of life: +The correct protein biosynthesis requires an accurate recognition of codons by anticodons + +----- + +General characteristics of Transfer RNA (tRNA) molecules + +• Each tRNA is a single chain containing between 73 and 93 nucleotides. +• The secondary structure resembles a cloverleaf +(~50% of the nucleotides are base-paired) +Five groups of bases are not base-paired, but participate in +hydrogen-bonding interactions: + • 3′ CCA terminal region (acceptor stem) + • TψC loop + • “extra arm” + • anticodon loop + • DHU loop +• The three-dimensional structure is L-shaped +• tRNAs contain 7 to 15 unusual bases + • methylated or demethylated derivatives +of A, U, C, and G + +⸻ + +• At the 3’ end, an activated amino acid is attached to a hydroxyl group of +adenosine in the CCA region of the acceptor stem + • the CCA region has the ability to change its conformation during protein synthesis +• The anticodon loop is near the center of the sequence +General characteristics of tRNA molecules + +⸻ + +Genetic code + +C G I +3’ 5’ +G C C +5’ 3’ +Codon +Anticodon +mRNA +• Genetic code: the relation between the sequence of bases in DNA +and the sequence of amino acids in proteins +mRNA +A U G G U G G C U A A G C G G U G A +Methionine Valine Alanine Lysine Arginine Stop +5’ 3’ +DNA +PROTEIN + +⸻ + +Amino acids are encoded by groups of three bases starting from a fixed point + +• Features of the Genetic code: +– three nucleotides (codon) encode an amino acid +– has directionality +– nonoverlapping +– has no punctuation +– is degenerate (most amino acids are encoded by more +than one codon) +mRNA +A U G G U G G C U A A G C G G U G A +Methionine Valine Alanine Lysine Arginine Stop +5’ 3’ +• 61 codons encode specify amino acids (20 in total) +• 3 codons are stop codons that designate termination +of translation. + +⸻ + +’Wobble’ effect in base-pairing + +’Wobble’ effect: Some tRNA molecules can recognize more than one codon +tRNA a.a. +1 +C G I +3’ 5’ +G C C +5’ 3’ +Codon +Anticodon +mRNA +tRNA a.a. +1 +C G I +3’ 5’ +G C A +5’ 3’ +Codon +Anticodon +mRNA + +⸻ + +’Wobble’ effect in base-pairing + +Anticodons base-pair with codons +’Wobble’ effect: Some tRNA molecules can recognize more than one codon +Codons that differ in either of their first two bases (from 5’) must be recognized by different tRNAs. +The first base of the anticodon (5’) determines the degree of wobble +• The redundancy, or degeneracy, of the genetic code indicates that recognition of +the third base of a codon is sometimes less discriminating than the other two +“wobble” = steric freedom in the pairing of the first base of the anticodon with the third base of the codon + +⸻ + +’Wobble’ effect in base-pairing + +“wobble hypothesis”: established hypothesis that predicts the binding of anticodons to codons +TABLE 30.2 Allowed pairings at the third base of the +codon according to the wobble hypothesis +Anticodons base-pair with codons +C +C +G + +⸻ + +’Wobble’ effect in base-pairing + +“wobble hypothesis”: established hypothesis that predicts the binding of anticodons to codons +TABLE 30.2 Allowed pairings at the third base of the +codon according to the wobble hypothesis +C +U +A/ +G + +⸻ + +’Wobble’ effect in base-pairing + +“wobble hypothesis”: established hypothesis that predicts the binding of anticodons to codons +TABLE 30.2 Allowed pairings at the third base of the codon +Example: If first base of the anticodon is inosine, the +anticodon can recognize three different codons +Inosine is formed by the deamination of adenosine + • has a heterocyclic nitrogen base that can form +hydrogen bonds with adenine, cytosine and uracil +The purine base inosine pairs with cytidine, uridine or adenosine + +⸻ + +Amino acids required for protein biosynthesis must first be attached to specific tRNA molecules + +• The attachment of a given amino acid to a particular tRNA establishes the genetic code +Aminoacyl-tRNA synthetases +Aminoacyl-tRNA synthetases attach specific amino acids to tRNAs +tRNA +amino acid +Aminoacyl-tRNA +amino + • acid + +⸻ + +Ester linkages couple amino acids to tRNA + +The process of attaching an amino acid to tRNA is called aminosylation +CCA arm of tRNA + • Amino acids are bound to the 3’end of the tRNA via an ester bond +between the carboxyl group on the amino acid and either the 2’ or 3’ +hydroxyl group of the terminal adenosine of the tRNA +3’ +Aminoacyl-tRNA: Amino acid bound to tRNA +3’ + +⸻ + +Each aminoacyl-tRNA synthetase is specific for a given amino acid + +How aminoacyl-tRNA synthetases evolve to differentiate between different amino acids? +A closer look at the amino acid threonine, valine and serine + +⸻ + +Threonyl-tRNA Synthetase contains an activation site + +Each aminoacyl-tRNA synthetase is specific for a given amino acid +How aminoacyl-tRNA synthetases evolve to differentiate Threonine, Valine and Serine? +Activation site +responsible for activating threonine by binding it +to adenosine triphospate (ATP) and further +transfer of these amino acid to the tRNA molecule +• Aminoacyl-tRNA synthetases have highly +discriminating amino acid activation sites + +⸻ + +Each aminoacyl-tRNA synthetase is specific for a given amino acid + +• To avoid coupling to the incorrect amino acid, threonyl-tRNA synthetase (tRNAThr) +contains a zinc ion at the active site that binds to the amino and hydroxyl groups +of threonine +• Valine is similar in overall structure to threonine but +lacks the hydroxyl group, so it does not bind to tRNAThr +• Serine is occasionally linked to tRNAThr because +of the presence of the hydroxyl group +(Thr) +(Val) +(Ser) +How aminoacyl-tRNA synthetases evolve to differentiate Threonine, Valine and Serine? + +⸻ + +Threonyl-tRNA Synthetase contains an activation site and an editing site + +Activation site +responsible for activating threonine by binding it +to adenosine triphospate (ATP) and further +transfer of these amino acid to the tRNA molecule +Editing site: +acts as a profreader and removes any incorrect +bound amino acid from the tRNA molecule + +⸻ + +Proofreading by Aminoacyl-tRNA Synthetases Increases the Fidelity of Protein Biosynthesis + +• Threonyl-tRNA synthetase has an editing site that hydrolyzes Serine if this +is linked to threonine-tRNA + • Because Thr contains an extra methyl group, it is sterically excluded +from the editing site + • The aminoacylated CCA arm of the tRNA is flexible and can swing out +of the activation site and into the editing site to remove Ser +• Most aminoacyl-tRNA synthetases contain editing sites and +activation sites to ensure very high fidelity. +Threonyl-tRNA synthetase Thr-tRNA + +⸻ + +Aminoacyl-tRNA synthetases interaction with tRNA + +Threonine-tRNA synthetase +tRNA +• Threonine-tRNA synthetases bind to both the acceptor stem +and the anticodon loop of the tRNA +Aminoacyl-tRNA synthetases assign a particular amino acid to a specific tRNA - the true translators of the genetic +code +• Some synthetases recognize their tRNA partners primarily on +the basis of their anticodons +• Synthetases may also recognize other +aspects of tRNA structure that vary among +different tRNAs + • many of the recognition sites are loops rich in +unusual bases +Number of interactions between tRNA +and aminoacyl-tRNA synsthetases + +⸻ + +The ribosome is the site of protein synthesis + +Ribosomes coordinate the interplay of aminoacyl-tRNAs, mRNA, and proteins +aminoacyl-tRNAs + +⸻ + +The E. coli ribosome has a sedimentation coefficient of 70S + +composed of: + • large (50S) subunit + • small (30S) subunit +34 proteins (L1–L34) +23S rRNA +5S rRNA +21 proteins (S1–S21) +16S rRNA +• Two-thirds of the mass of ribosomes is RNA +• Ribosomal RNA (rRNA) is the catalyst for protein synthesis + +⸻ + +The ribosome has three binding sites for transfer RNAs + +• Three tRNA-binding sites: + • A site (aminoacyl) + • P site (peptidyl) + • E site (exit) +• mRNA fragment is bound within the 30S subunit +• Each tRNA contacts both 30S and 50S subunits + +⸻ + +Overview of mechanism of protein biosynthesis + +Initiation, Elongation, Translocation and Termination +Initiation + +⸻ + +Initiation of translation + +• Each initiator region usually displays: + • start codon: AUG (Met) or sometimes GUG, rarely UUG + • purine-rich sequence ~10 nt upstream +• Bacterial mRNAs often encode several polypeptides +• Shine–Dalgarno sequence = purine-rich region binding rRNA to position initiator codon in P site + +⸻ + +Bacterial protein synthesis is initiated by N-formylmethionyl-transfer RNA + +Steps: + 1. Met linked to tRNAfMet by aminoacyl-tRNA synthetase + 2. Met amino group is formylated + 3. fMet-tRNAfMet placed in P site +(note: tRNAMet inserts internal Met) + +⸻ + +Initiation factors (IF1, IF2, IF3) + 1. IF1 + IF3 bind 30S to prevent premature binding to 50S + 2. IF2(GTP) + fMet-tRNAfMet + mRNA bind to 30S → 30S initiation complex + 3. Structural changes release IF1 + IF3 + 4. IF2 stimulates 50S binding + GTP hydrolysis → 70S initiation complex +Streptomycin binds 30S and blocks fMet-tRNAfMet binding (bacteria) + +⸻ + +Elongation + +Elongation factors deliver aminoacyl-tRNAs to the ribosome + +⸻ + +Elongation factors deliver aminoacyl-tRNAs + +Steps: + 1. EF-Tu-GTP binds aminoacyl-tRNA → delivers to A site + 2. Correct codon recognition → GTP hydrolysis → EF-Tu-GDP leaves + 3. EF-Ts binds EF-Tu-GDP + 4. EF-Ts releases GDP → GTP binds → EF-Tu-GTP regenerated +Tetracycline binds 30S → blocks aminoacyl-tRNA binding + +⸻ + +Elongation – peptidyl transferase + +• Amino group of A-site tRNA attacks carbonyl of P-site peptidyl-tRNA +• Peptidyl transferase center on 50S catalyzes peptide bond formation +• Reaction is thermodynamically spontaneous but accelerated by ribosome positioning/orientation + +⸻ + +Translocation + +Translocation repositions tRNAs and mRNA +EF-G (translocase) catalyzes 1-codon movement (requires GTP) + 1. EF-G-GTP binds near A site + 2. GTP hydrolysis → conformational change → peptidyl-tRNA shifts A→P +After peptide bond formation: chain is in P site (50S), anticodon still in A site (30S) + +⸻ + +Termination + +Release factors (RFs): +• RF1 + RF2 recognize stop codons (UAA, UGA, UAG) +• RF3 (GTPase) removes RF1/RF2 +RF1/RF2 bind stop codon in A site +RFs contain conserved GGQ motif with methylated Gln → promotes hydrolysis of ester linkage → releases polypeptide + +⸻ + +Bacteria: transcription and translation are coupled + +Minimal time gap between transcription and translation +Polysome: multiple ribosomes translating one mRNA simultaneously + +⸻ + +Difference between bacterial and eukaryotic protein biosynthesis + +Bacteria 70S: 50S+30S +Eukaryotes 80S: 60S+40S +Initiation differences: +• Initiating amino acid = Met (not fMet) +• No Shine–Dalgarno +• Start site usually first AUG from 5’ end +• Many more eIFs +Eukaryotic mRNA circularization: 5’-cap proteins + PABP at 3’-poly(A) interact → circular mRNA + +⸻ + +TABLE 30.4 Antibiotic inhibitors of protein biosynthesis + +Streptomycin/aminoglycosides — inhibit initiation + misreading (bacteria) +Tetracycline — blocks aminoacyl-tRNA binding (30S) +Chloramphenicol — inhibits peptidyl transferase (50S) +Cycloheximide — inhibits translocation (eukaryotes) +Erythromycin — blocks translocation (50S) +Puromycin — premature termination (aa-tRNA analog) + +⸻ + +Diphtheria toxin + +Blocks protein biosynthesis in eukaryotes by inhibiting translocation + +⸻ + +Concepts + +DNA +RNA +Protein +Translation +Transcription +Messenger RNA (mRNA) +Initiation factors +Elongation factors +Release factors +Aminoacyl tRNA synthetases +Transfer RNA (tRNA) +Ribosome (ribosomal RNA + proteins) +EF1 EF2 EF3 +EF-Tu EF-Ts EF-G +RF1 RF2 RF3 +• Genetic code +• Degeneracy +• Codon +• Anticodon +• Transfer RNA +• ’Wobble’ effect +• Aminoacyl-tRNA synthetases +• Aminoacyl-tRNA +• Aminosylation +• Aminoacyl-tRNA synthetases activation site +• Aminoacyl-tRNA synthetases editing site +• Ribosome +• Ribosomal RNA +• Ribosome E site, P site and A site +• Shine-Dalgarno sequence +• Initiation, elongation, translocation, termination +• Initiation factors +• Elongation factors +• Termination factors +• Polysome +• Inhibition of trancription diff --git a/content/Biokemi/Cellulära processer/Translation/H25_Translation.pdf b/content/Biokemi/Cellulära processer/Translation/Slides.pdf.pdf similarity index 100% rename from content/Biokemi/Cellulära processer/Translation/H25_Translation.pdf rename to content/Biokemi/Cellulära processer/Translation/Slides.pdf.pdf diff --git a/content/Biokemi/Cellulära processer/Translation/Stoff.md b/content/Biokemi/Cellulära processer/Translation/Stoff.md new file mode 100644 index 0000000..414d0c4 --- /dev/null +++ b/content/Biokemi/Cellulära processer/Translation/Stoff.md @@ -0,0 +1,32 @@ +``` +mRNA kodas i 5'-till-3'-riktning ett kodon i taget +Proteinet är syntetiserat från amino- till karboxyl-riktning +tRNA är en adaptormolekyl mellan kodonet och aminosyran +antikodonet parar med kodonet och är komplementar, innehåller samma information bakvänt +För att kunna syntetisera protein måste kodonet läsas av korrekt av antikodonen +tRNA är en kedja som innehåller mellan 73 och 93 nukleotider +tRNA innehåller 7 till 15 ovanliga baser, metylerade eller demetylerade derivat +Sekundärstruktuern av tRNA ser ut som ett klöverlöv +Fem grupper av bases i tRNA är inte basparade men deltar i vätebindingar +tRNAs sätter fast aminosyror i 3 CCA-terminalaregionen som också heter acceptor stem +tRNAs 3' ände har först en adenosine med en hydroxylgrupp som sitter fast med aminosyran +tRNAs 3D-struktur ser ut som ett L +tRNAs antikodonloop sitter i mitten av sekvensen +Genetiska koden är relationen mellan basparen i DNA och sekvensen av aminosyror i proteiner +Genetiska koden karakteriseras av: 3 nukleotider (kodon), går i en riktning, överlappar inte, ingen punktuation +Den genetiska koden är degenererad: flera kodon kodar för samma aminosyra, vilket minskar effekten av vanliga mutationer +Det finns 3 kodon sekvenser som terminerar translationen (UAA, UAG, UGA) +61 kodon kodar för 20 aminosyror +Vissa tRNA-molekyler kan känna igen fler än ett kodon, det heter Wobble-effekten +Den tredje nukleotiden i ett kodon kan ’svaja’ lite, den har större sterisk frihet och behöver inte alltid baspara strikt +Svajhypotesen förutser vilket antikodon som kan binda till ett visst kodon +Inosin bildas genom deaminering av adenosin och kan bilda vätebindningar med adenin, cytosin och uracil +Aminoacyl-tRNA-syntetaser kopplar specifika aminosyror till tRNA +När man kopplar en aminosyra till tRNA heter det aminoacylisering +Aminosyror kopplar till 2' eller 3'-hydroxylgruppen på det terminala adenosin i tRNA +Varje aminosyra har ett specifikt enzym (aminoacyl-tRNA-syntetas), som katalyserar kopplingen av just den aminosyran till rätt tRNA-molekyl. +Aminoacyl-tRNA-syntetas har en redigeringsplats som korrekturläser och tar bort felaktigt bundna aminosyror +Aminoacyl-tRNA-syntetas har en aktiveringsplats som aktiverar rätt aminosyra genom att binda den till ATP innan den förs över till tRNA. +Aktiveringsplatsen försöker välja rätt aminosyra, och redigeringsplatsen fångar upp och tar bort de små fel som ändå passerar vilket ger mycket hög noggrannhet. + +``` \ No newline at end of file diff --git a/content/Pasted image 20251125093128.png b/content/Pasted image 20251125093128.png new file mode 100644 index 0000000..c19aa94 Binary files /dev/null and b/content/Pasted image 20251125093128.png differ