{"id":1036285,"date":"2012-03-18T15:46:02","date_gmt":"2012-03-18T15:46:02","guid":{"rendered":"http:\/\/www.immortalitymedicine.tv\/biotechnology\/competition-between-pentoses-and-glucose-during-uptake-and-catabolism-in-recombinant-saccharomyces-cerevisiae.php"},"modified":"2024-08-17T15:55:09","modified_gmt":"2024-08-17T19:55:09","slug":"competition-between-pentoses-and-glucose-during-uptake-and-catabolism-in-recombinant-saccharomyces-cerevisiae","status":"publish","type":"post","link":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/biotechnology\/competition-between-pentoses-and-glucose-during-uptake-and-catabolism-in-recombinant-saccharomyces-cerevisiae.php","title":{"rendered":"Competition between pentoses and glucose during uptake and catabolism in recombinant Saccharomyces cerevisiae"},"content":{"rendered":"<p>Background:<br \/>\nIn mixed sugar fermentations with recombinant Saccharomyces cerevisiae strains able to ferment D-xylose and L-arabinose the pentose sugars are normally only utilized after depletion of D-glucose. This has been attributed to competitive inhibition of pentose uptake by D-glucose as pentose sugars are taken up into yeast cells by individual members of the yeast hexose transporter family. We wanted to investigate whether D-glucose inhibits pentose utilization only by blocking its uptake or also by interfering with its further metabolism.<br \/>\nResults:<br \/>\nTo distinguish between inhibitory effects of D-glucose on pentose uptake and pentose catabolism, maltose was used as an alternative carbon source in maltose-pentose co-consumption experiments. Maltose is taken up by a specific maltose transport system and hydrolyzed only intracellularly into two D-glucose molecules. Pentose consumption decreased by about 20 - 30% during the simultaneous utilization of maltose indicating that hexose catabolism can impede pentose utilization. To test whether intracellular D-glucose might impair pentose utilization, hexo-\/glucokinase deletion mutants were constructed. Those mutants are known to accumulate intracellular D-glucose when incubated with maltose. However, pentose utilization was not effected in the presence of maltose. Addition of increasing concentrations of D-glucose to the hexo-\/glucokinase mutants finally completely blocked D-xylose as well as L-arabinose consumption, indicating a pronounced inhibitory effect of D-glucose on pentose uptake. Nevertheless, constitutive overexpression of pentose-transporting hexose transporters like Hxt7 and Gal2 could improve pentose consumption in the presence of D-glucose.<br \/>\nConclusion:<br \/>\nOur results confirm that D-glucose impairs the simultaneous utilization of pentoses mainly due to inhibition of pentose uptake. Whereas intracellular D-glucose does not seem to have an inhibitory effect on pentose utilization, further catabolism of D-glucose can also impede pentose utilization. Nevertheless, the results suggest that co-fermentation of pentoses in the presence of D-glucose can significantly be improved by the overexpression of pentose transporters, especially if they are not inhibited by D-glucose.Source:<br \/><a href=\"http:\/\/www.biotechnologyforbiofuels.com\/rss\/\">http:\/\/www.biotechnologyforbiofuels.com\/rss\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Background: In mixed sugar fermentations with recombinant Saccharomyces cerevisiae strains able to ferment D-xylose and L-arabinose the pentose sugars are normally only utilized after depletion of D-glucose. This has been attributed to competitive inhibition of pentose uptake by D-glucose as &hellip; <a href=\"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/biotechnology\/competition-between-pentoses-and-glucose-during-uptake-and-catabolism-in-recombinant-saccharomyces-cerevisiae.php\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"limit_modified_date":"","last_modified_date":"","_lmt_disableupdate":"","_lmt_disable":"","footnotes":""},"categories":[1246860],"tags":[],"class_list":["post-1036285","post","type-post","status-publish","format-standard","hentry","category-biotechnology"],"modified_by":null,"_links":{"self":[{"href":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/wp-json\/wp\/v2\/posts\/1036285"}],"collection":[{"href":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/wp-json\/wp\/v2\/comments?post=1036285"}],"version-history":[{"count":0,"href":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/wp-json\/wp\/v2\/posts\/1036285\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/wp-json\/wp\/v2\/media?parent=1036285"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/wp-json\/wp\/v2\/categories?post=1036285"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/wp-json\/wp\/v2\/tags?post=1036285"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}