{"id":315,"date":"2023-03-15T15:22:56","date_gmt":"2023-03-15T15:22:56","guid":{"rendered":"https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/?post_type=chapter&#038;p=315"},"modified":"2023-04-07T11:26:55","modified_gmt":"2023-04-07T11:26:55","slug":"315","status":"publish","type":"chapter","link":"https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/chapter\/315\/","title":{"raw":"Prokaryotic Translation Elongation &amp; Termination","rendered":"Prokaryotic Translation Elongation &amp; Termination"},"content":{"raw":"<h1>Elongation<\/h1>\r\n<ul>\r\n \t<li><span>Elongation includes repetitive cycles of decoding the m RNA , peptide bond formation, and translocation. <\/span><\/li>\r\n \t<li><span>Elongation begins as soon as the second codon of the ORF becomes accessible for reading by the next amino acylated tRNAs\u00a0<\/span><\/li>\r\n \t<li><span>\u00a0Elongation is facilitated by\u00a0 translation factors EF-Tu, EF-G ,EF-Ts EF-P and EF-4.<\/span><\/li>\r\n<\/ul>\r\n<table>\r\n<tbody>\r\n<tr>\r\n<td><strong>Bacterial Elongation Factors <\/strong><\/td>\r\n<td><strong>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Function<\/strong><\/td>\r\n<\/tr>\r\n<tr>\r\n<td>EF-TU<\/td>\r\n<td>mediates the entry of the aminoacyl\u00a0t RNA\u00a0into a free site of the\u00a0ribosome<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>EF-TS<\/td>\r\n<td>serves as the guanine nucleotide exchange factor \u00a0for EF-Tu and catalyzes \u00a0the release of GDP from EF-Tu.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>EF-G<\/td>\r\n<td>catalyzes the translocation of the tRNA and mRNA down the ribosome.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>EF-P<\/td>\r\n<td>possibly stimulates formation of peptide bonds and resolves stalls.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>EF-4<\/td>\r\n<td>Proofreading<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<ul>\r\n \t<li style=\"text-align: justify\"><span>The second\u00a0 codon\u00a0 in the P site is recognized by aminoacylated -tRNAs.\u00a0 A ternary complex of\u00a0 aa-tRANA ,EF-Tu and GTP is attached to the P site .This i<\/span><span>nteraction triggers GTP hydrolysis by EF-Tu. After Pi release, EF-Tu rearranges into the guanosine diphosphate (GDP)-bound form and releases the aa-tRNA.<\/span><\/li>\r\n \t<li style=\"text-align: justify\"><span>The amino group of the amino acid attached to the A-site tRNA\u00a0 makes a peptide bond with the carboxyl group of the amino acid attached to the P-site tRNA. This reaction is catalyzed by <strong>peptidyl transferase<\/strong>, an RNA-based ribozyme that is integrated into the 50S ribosomal subunit. Now the A site carries a peptide comprising of two amino acids and leaves the uncharged t RNA in the p site .<\/span><\/li>\r\n \t<li style=\"text-align: justify\">During elongation the ribosomes move one codon along the mRNA in a process called <strong>Translocation.<\/strong> <span>Translocation is promoted by EF-G at the cost of GTP hydrolysis .<\/span>During each translocation event, a new\u00a0 charged tRNAs enter at the A site, then shift to the P site, and then finally to the E site for removal. Ribosomal movements\u00a0 are induced by conformational changes that advance the ribosome by three bases in the 3\u2032 direction.<\/li>\r\n \t<li style=\"text-align: justify\">This process of elongation continues until <span>the ribosome arrives at the stop codon.<\/span><\/li>\r\n \t<li style=\"text-align: justify\"><span>Amazingly, the <\/span><em>E. coli<\/em><span>\u00a0translation apparatus takes only 0.05 seconds to add each amino acid, meaning that a 200 amino-acid protein can be translated in just 10 seconds.<\/span><\/li>\r\n<\/ul>\r\n<h2>Termination<\/h2>\r\n<ul>\r\n \t<li><span>Termination occurs when the ribosome encounters a stop codon UAG\/UAA and UGA\/UAA, respectively in the mRNA.<\/span><\/li>\r\n \t<li><span>These stop codons are recognized by the termination (or release) factors RF1 and RF2.<\/span><\/li>\r\n \t<li><span>Another termination factor, RF3, facilitates turnover of RF1 and RF2 but is not required for peptidyl-tRNA hydrolysis.<\/span><\/li>\r\n \t<li><span>The mechanism of termination encompasses\u00a0 three steps: <\/span>\r\n<ul>\r\n \t<li><span>recognition of the stop codon, <\/span><\/li>\r\n \t<li><span>hydrolysis of the ester bond of the peptidyl-tRNA (these two steps are accomplished by RF1 or RF2) and <\/span><\/li>\r\n \t<li><span>dissociation of RF1\/RF2 with the help of RF3.<\/span><\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<section id=\"fs-id1986668\" class=\" focusable\" data-depth=\"1\"><section id=\"fs-id2217094\" class=\" focusable\" data-depth=\"2\">\r\n<ul>\r\n \t<li id=\"fs-id2155698\">The releasing factors instruct peptidyl transferase to add a water molecule to the carboxyl end of the P-site amino acid. This reaction forces the P-site amino acid to detach from its tRNA, and releases the\u00a0 newly made protein.<\/li>\r\n \t<li>The small and large ribosomal subunits dissociate from the mRNA and from each other; they are recruited almost immediately into another translation initiation complex. After many ribosomes have completed translation, the mRNA is degraded so the nucleotides can be reused in another transcription reaction.<\/li>\r\n<\/ul>\r\n<\/section><\/section><img src=\"http:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-content\/uploads\/sites\/17\/2023\/03\/Translation-in-bacteria-1024x710.jpg\" alt=\"Picture depicting the initian,elongation and termination of translation in prokaryotes\" width=\"1024\" height=\"710\" class=\"aligncenter size-large wp-image-456\" \/>\r\n\r\n&nbsp;\r\n<p style=\"text-align: center\"><span style=\"background-color: #ffffff\"><a href=\"https:\/\/courses.lumenlearning.com\/wm-biology1\/chapter\/prokaryotic-translation\/\" target=\"_blank\" rel=\"noopener\" style=\"background-color: #ffffff\">\"T<span style=\"color: #993366\">ranslation in bacteria\"<\/span><\/a><span style=\"color: #993366\">\u00a0by\u00a0<a style=\"color: #993366;background-color: #ffffff\">Biology 2e. Provided by: OpenStax<\/a><a style=\"color: #993366;background-color: #ffffff\"><\/a><a style=\"color: #993366;background-color: #ffffff\"><\/a>\u00a0is licensed under\u00a0<a href=\"http:\/\/creativecommons.org\/licenses\/by\/4.0\" target=\"_blank\" rel=\"noopener\" style=\"color: #993366;background-color: #ffffff\">CC BY 4.0<\/a><\/span><\/span><\/p>\r\n&nbsp;\r\n\r\n<section id=\"fs-id1986668\" class=\" focusable\" data-depth=\"1\"><section id=\"fs-id2217094\" class=\" focusable\" data-depth=\"2\">\r\n<p id=\"fs-id2155698\"><\/p>\r\n\r\n<\/section><\/section>","rendered":"<h1>Elongation<\/h1>\n<ul>\n<li><span>Elongation includes repetitive cycles of decoding the m RNA , peptide bond formation, and translocation. <\/span><\/li>\n<li><span>Elongation begins as soon as the second codon of the ORF becomes accessible for reading by the next amino acylated tRNAs\u00a0<\/span><\/li>\n<li><span>\u00a0Elongation is facilitated by\u00a0 translation factors EF-Tu, EF-G ,EF-Ts EF-P and EF-4.<\/span><\/li>\n<\/ul>\n<table>\n<tbody>\n<tr>\n<td><strong>Bacterial Elongation Factors <\/strong><\/td>\n<td><strong>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Function<\/strong><\/td>\n<\/tr>\n<tr>\n<td>EF-TU<\/td>\n<td>mediates the entry of the aminoacyl\u00a0t RNA\u00a0into a free site of the\u00a0ribosome<\/td>\n<\/tr>\n<tr>\n<td>EF-TS<\/td>\n<td>serves as the guanine nucleotide exchange factor \u00a0for EF-Tu and catalyzes \u00a0the release of GDP from EF-Tu.<\/td>\n<\/tr>\n<tr>\n<td>EF-G<\/td>\n<td>catalyzes the translocation of the tRNA and mRNA down the ribosome.<\/td>\n<\/tr>\n<tr>\n<td>EF-P<\/td>\n<td>possibly stimulates formation of peptide bonds and resolves stalls.<\/td>\n<\/tr>\n<tr>\n<td>EF-4<\/td>\n<td>Proofreading<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<ul>\n<li style=\"text-align: justify\"><span>The second\u00a0 codon\u00a0 in the P site is recognized by aminoacylated -tRNAs.\u00a0 A ternary complex of\u00a0 aa-tRANA ,EF-Tu and GTP is attached to the P site .This i<\/span><span>nteraction triggers GTP hydrolysis by EF-Tu. After Pi release, EF-Tu rearranges into the guanosine diphosphate (GDP)-bound form and releases the aa-tRNA.<\/span><\/li>\n<li style=\"text-align: justify\"><span>The amino group of the amino acid attached to the A-site tRNA\u00a0 makes a peptide bond with the carboxyl group of the amino acid attached to the P-site tRNA. This reaction is catalyzed by <strong>peptidyl transferase<\/strong>, an RNA-based ribozyme that is integrated into the 50S ribosomal subunit. Now the A site carries a peptide comprising of two amino acids and leaves the uncharged t RNA in the p site .<\/span><\/li>\n<li style=\"text-align: justify\">During elongation the ribosomes move one codon along the mRNA in a process called <strong>Translocation.<\/strong> <span>Translocation is promoted by EF-G at the cost of GTP hydrolysis .<\/span>During each translocation event, a new\u00a0 charged tRNAs enter at the A site, then shift to the P site, and then finally to the E site for removal. Ribosomal movements\u00a0 are induced by conformational changes that advance the ribosome by three bases in the 3\u2032 direction.<\/li>\n<li style=\"text-align: justify\">This process of elongation continues until <span>the ribosome arrives at the stop codon.<\/span><\/li>\n<li style=\"text-align: justify\"><span>Amazingly, the <\/span><em>E. coli<\/em><span>\u00a0translation apparatus takes only 0.05 seconds to add each amino acid, meaning that a 200 amino-acid protein can be translated in just 10 seconds.<\/span><\/li>\n<\/ul>\n<h2>Termination<\/h2>\n<ul>\n<li><span>Termination occurs when the ribosome encounters a stop codon UAG\/UAA and UGA\/UAA, respectively in the mRNA.<\/span><\/li>\n<li><span>These stop codons are recognized by the termination (or release) factors RF1 and RF2.<\/span><\/li>\n<li><span>Another termination factor, RF3, facilitates turnover of RF1 and RF2 but is not required for peptidyl-tRNA hydrolysis.<\/span><\/li>\n<li><span>The mechanism of termination encompasses\u00a0 three steps: <\/span>\n<ul>\n<li><span>recognition of the stop codon, <\/span><\/li>\n<li><span>hydrolysis of the ester bond of the peptidyl-tRNA (these two steps are accomplished by RF1 or RF2) and <\/span><\/li>\n<li><span>dissociation of RF1\/RF2 with the help of RF3.<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<section id=\"fs-id1986668\" class=\"focusable\" data-depth=\"1\">\n<section id=\"fs-id2217094\" class=\"focusable\" data-depth=\"2\">\n<ul>\n<li id=\"fs-id2155698\">The releasing factors instruct peptidyl transferase to add a water molecule to the carboxyl end of the P-site amino acid. This reaction forces the P-site amino acid to detach from its tRNA, and releases the\u00a0 newly made protein.<\/li>\n<li>The small and large ribosomal subunits dissociate from the mRNA and from each other; they are recruited almost immediately into another translation initiation complex. After many ribosomes have completed translation, the mRNA is degraded so the nucleotides can be reused in another transcription reaction.<\/li>\n<\/ul>\n<\/section>\n<\/section>\n<p><img decoding=\"async\" src=\"http:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-content\/uploads\/sites\/17\/2023\/03\/Translation-in-bacteria-1024x710.jpg\" alt=\"Picture depicting the initian,elongation and termination of translation in prokaryotes\" width=\"1024\" height=\"710\" class=\"aligncenter size-large wp-image-456\" srcset=\"https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-content\/uploads\/sites\/17\/2023\/03\/Translation-in-bacteria-1024x710.jpg 1024w, https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-content\/uploads\/sites\/17\/2023\/03\/Translation-in-bacteria-300x208.jpg 300w, https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-content\/uploads\/sites\/17\/2023\/03\/Translation-in-bacteria-768x533.jpg 768w, https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-content\/uploads\/sites\/17\/2023\/03\/Translation-in-bacteria-65x45.jpg 65w, https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-content\/uploads\/sites\/17\/2023\/03\/Translation-in-bacteria-225x156.jpg 225w, https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-content\/uploads\/sites\/17\/2023\/03\/Translation-in-bacteria-350x243.jpg 350w, https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-content\/uploads\/sites\/17\/2023\/03\/Translation-in-bacteria.jpg 1299w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/p>\n<p>&nbsp;<\/p>\n<p style=\"text-align: center\"><span style=\"background-color: #ffffff\"><a href=\"https:\/\/courses.lumenlearning.com\/wm-biology1\/chapter\/prokaryotic-translation\/\" target=\"_blank\" rel=\"noopener\" style=\"background-color: #ffffff\">&#8220;T<span style=\"color: #993366\">ranslation in bacteria&#8221;<\/span><\/a><span style=\"color: #993366\">\u00a0by\u00a0<a style=\"color: #993366;background-color: #ffffff\">Biology 2e. Provided by: OpenStax<\/a><a style=\"color: #993366;background-color: #ffffff\"><\/a><a style=\"color: #993366;background-color: #ffffff\"><\/a>\u00a0is licensed under\u00a0<a href=\"http:\/\/creativecommons.org\/licenses\/by\/4.0\" target=\"_blank\" rel=\"noopener\" style=\"color: #993366;background-color: #ffffff\">CC BY 4.0<\/a><\/span><\/span><\/p>\n<p>&nbsp;<\/p>\n<section class=\"focusable\" data-depth=\"1\">\n<section class=\"focusable\" data-depth=\"2\">\n<\/section>\n<\/section>\n","protected":false},"author":5,"menu_order":18,"template":"","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_uf_show_specific_survey":0,"_uf_disable_surveys":false,"pb_show_title":"on","pb_short_title":"Prokaryotic Translation Elongation & Termination","pb_subtitle":"Prokaryotic Translation Elongation & Termination","pb_authors":["dr-v-malathi"],"pb_section_license":"cc-by-sa"},"chapter-type":[],"contributor":[61],"license":[54],"class_list":["post-315","chapter","type-chapter","status-publish","hentry","contributor-dr-v-malathi","license-cc-by-sa"],"aioseo_notices":[],"part":3,"_links":{"self":[{"href":"https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-json\/pressbooks\/v2\/chapters\/315","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-json\/wp\/v2\/users\/5"}],"version-history":[{"count":31,"href":"https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-json\/pressbooks\/v2\/chapters\/315\/revisions"}],"predecessor-version":[{"id":1004,"href":"https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-json\/pressbooks\/v2\/chapters\/315\/revisions\/1004"}],"part":[{"href":"https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-json\/pressbooks\/v2\/parts\/3"}],"metadata":[{"href":"https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-json\/pressbooks\/v2\/chapters\/315\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-json\/wp\/v2\/media?parent=315"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-json\/pressbooks\/v2\/chapter-type?post=315"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-json\/wp\/v2\/contributor?post=315"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.justwrite.in\/understanding-gene-regulation\/wp-json\/wp\/v2\/license?post=315"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}