tag:blogger.com,1999:blog-37148773.post7337072537446938528..comments2024-03-27T14:50:47.345-04:00Comments on <center>Sandwalk</center>: Monday's Molecule #174Larry Moranhttp://www.blogger.com/profile/05756598746605455848noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-37148773.post-31960740829078156412012-06-25T09:59:39.050-04:002012-06-25T09:59:39.050-04:00Thank-you for that update. I've read the paper...Thank-you for that update. I've read the papers and I'll be adding the biosynthesis of pyrrolysine to the animo acid metabolism chapter in the next edition of my textbook!Larry Moranhttps://www.blogger.com/profile/05756598746605455848noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-2676009553688574092012-06-24T21:57:17.171-04:002012-06-24T21:57:17.171-04:00UPDATE: The molecule is pyrrolysine, an amino acid...UPDATE: The molecule is pyrrolysine, an amino acid found in the proteins of some species of archaebacteria. Pyrrolysine is made from lysyl-tRNA that is subsequently incorporated into protein during translation.<br />*************************<br />It is also found in eubacteria (Nozawa et al Nature 2009)<br /><br />Pyl is synthesized in a tRNA-INdependent manner (Gaston et al Nature 2011; Longstaff et al PNAS 2007)<br /><br />The initial paper from Krzycki suggested Lys was aminoacylated to tRNA(Pyl) (Srinivasan et al Science 2002). However work in the Soll lab showed Lys could be attached using a two different LysRS enzymes. (Polycarpo et al Mol Cell 2003).<br /><br />Later the Soll lab showed PylRS could directly ligate Pyl to its tRNA (Polycarpo et al PNAS 2004). Very soon after the Krzycki lab showed a similar result (Blight et al Nature 2004). In that Nature paper the contradicting results were only briefly mentioned (blamed on where the His-tag was added, N- vs. C-terminus). I don't think anyone has followed up that hypothesis.ponderingfoolnoreply@blogger.comtag:blogger.com,1999:blog-37148773.post-53415302932529547212012-06-19T11:26:18.344-04:002012-06-19T11:26:18.344-04:00This is pyrrolysine, a modified form of lysine fou...This is pyrrolysine, a modified form of lysine found mainly in proteins in methanogenic bacteria. <br /><br />It is unusual in that rather than lysine being post-translationally modified is to this molecule, it is incorporated directly into the proteins. Lysine is also present, so there are 21 "natural" amino acids in proteins in these organisms. The genetic code in these organisms is different in this respect. <br /><br />Bill ChaneyBill Chaneynoreply@blogger.comtag:blogger.com,1999:blog-37148773.post-82140238371398499912012-06-18T22:35:36.349-04:002012-06-18T22:35:36.349-04:00This is Pyrrolysine (L in its naturally occurring ...This is Pyrrolysine (L in its naturally occurring form) <br /><br />Wikipedia defines it:<br />"Pyrrolysine (abbreviated as Pyl or O) is a naturally occurring, genetically coded amino acid used by some methanogenic archaea and one known bacterium in enzymes that are part of their methane-producing metabolism. It is similar to lysine, but with an added pyrroline ring linked to the end of the lysine side chain. Produced by a specific tRNA and aminoacyl tRNA synthetase, it forms part of an unusual genetic code in these organisms, and is considered the 22nd proteinogenic amino acid."<br /><br />Wow so that is why it was such a significant discovery, a 22nd proteinogenic amino acid, an extra amino acid in the genetic code. Things have certainly changed since I was a biochemistry undergraduate 40 years ago. I keep saying to myself I must learn about the archaeabacteria but I just never get around to it.chemicalscumhttps://www.blogger.com/profile/00456611765432242326noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-44534652539317333362012-06-18T14:41:23.686-04:002012-06-18T14:41:23.686-04:00Damn, beat me to it...*sigh*Damn, beat me to it...*sigh*Sean Ridouthttps://www.blogger.com/profile/17920913146530127438noreply@blogger.comtag:blogger.com,1999:blog-37148773.post-29984281577428666362012-06-18T14:31:57.095-04:002012-06-18T14:31:57.095-04:00This comment has been removed by a blog administrator.Raul A. FĂ©lix de Sousanoreply@blogger.com