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Class I and class II lysyl‐tRNA synthetase mutants and the genetic encoding of pyrrolysine in Methanosarcina spp.
Author(s) -
Mahapatra Anirban,
Srinivasan Gayathri,
Richter Kerstin B.,
Meyer Andrew,
Lienard Tanja,
Zhang Jun Kai,
Zhao Gang,
Kang Patrick T.,
Chan Michael,
Gottschalk Gerhard,
Metcalf William W.,
Krzycki Joseph A.
Publication year - 2007
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2007.05740.x
Subject(s) - biology , methanosarcina barkeri , methanosarcina , biochemistry , transfer rna , methanogenesis , mutant , methylamines , methyltransferase , methylamine , microbiology and biotechnology , genetics , gene , archaea , methylation , rna , bacteria
Summary Methanosarcina spp. begin methanogenesis from methylamines with methyltransferases made via the translation of UAG as pyrrolysine. In vitro evidence indicates two possible routes to pyrrolysyl‐tRNA Pyl . PylS ligates pyrrolysine to tRNA Pyl . Alternatively, class I and class II lysyl‐tRNA synthetases (LysRS1 and LysRS2) together form lysyl‐tRNA Pyl , a potential intermediate to pyrrolysyl‐tRNA Pyl . The unusual possession of both LysRS1 and LysRS2 by Methanosarcina spp. may also reflect differences in catalytic properties. Here we assessed the in vivo relevance of these hypotheses. The lysK and mtmB transcripts, encoding LysRS1 and monomethylamine methyltransferase, were detectable in Methanosarcina barkeri during early log growth on trimethylamine, but not methanol. In contrast, lysS transcript encoding LysRS2 was detectable during log phase with either substrate. Methanosarcina acetivorans strains bearing deletions of lysK or lysS grew normally on methanol and methylamines with wild‐type levels of monomethylamine methyltransferase and aminoacyl‐tRNA Pyl . The lysK and lysS genes could not replace pylS in a recombinant system employing tRNA Pyl for UAG suppression. The results support an association of LysRS1 with growth on methylamine, but not an essential role for LysRS1/LysRS2 in the genetic encoding of pyrrolysine. However, decreased lysyl‐tRNA Lys in the lysS mutant provides a possible rationale for stable transfer of the bacterial lysS gene to methanoarchaea.