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Clustered genes required for synthesis and deposition of envelope glycolipids in Anabaena sp. strain PCC 7120
Author(s) -
Fan Qing,
Huang Guocun,
LechnoYossef Sigal,
Wolk C. Peter,
Kaneko Takakazu,
Tabata Satoshi
Publication year - 2005
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.1365-2958.2005.04818.x
Subject(s) - heterocyst , biology , orfs , glycolipid , nitrogenase , anabaena , cyanobacteria , gene , complementation , mutant , microbiology and biotechnology , biochemistry , genetics , open reading frame , botany , peptide sequence , bacteria , nitrogen fixation
Summary Photoreduction of dinitrogen by heterocyst‐forming cyanobacteria is of great importance ecologically and for subsistence rice agriculture. Their heterocysts must have a glycolipid envelope layer that limits the entry of oxygen if nitrogenase is to remain active to f ix dinitrogen in an ox ygen‐containing milieu (the Fox + phenotype). Genes alr5354 ( hglD ), alr5355 ( hglC ) and alr5357 ( hglB ) of the filamentous cyanobacterium, Anabaena sp. strain PCC 7120, and hglE of Nostoc punctiforme are required for synthesis of heterocyst envelope glycolipids. Newly identified Fox – mutants bear transposons in nearby open reading frames (orfs) all5343 , all5345–asr5349 and alr5351–alr5358 . Complementation and other analysis provide evidence that at least orfs all5343 (or a co‐transcribed gene), all5345 , all5347 , alr5348 , asr5350–alr5353 and alr5356 , but not asr5349 , are also required for a Fox + phenotype. Lipid and sequence analyses suggest that alr5351–alr5357 encode the enzymes that biosynthesize the glycolipid aglycones. Electron microscopy indicates a role of all5345 through all5347 in the normal deposition of the envelope glycolipids.