THE HGLK GENE IS REQUIRED FOR LOCALIZATION OF HETEROCYST-SPECIFIC GLYCOLIPIDS IN THE CYANOBACTERIUM ANABAENA SP STRAIN PCC-7120

被引:90
作者
BLACK, K [1 ]
BUIKEMA, WJ [1 ]
HASELKORN, R [1 ]
机构
[1] UNIV CHICAGO, DEPT MOLEC GENET & CELL BIOL, CHICAGO, IL 60637 USA
关键词
D O I
10.1128/jb.177.22.6440-6448.1995
中图分类号
Q93 [微生物学];
学科分类号
071005 ; 100705 ;
摘要
Mutant strain 543 of the cyanobacterium Anabaena sp. strain PCC 7120 was originally isolated as a Fox mutant following chemical mutagenesis. Ultrastructural analysis shows that in nitrogen-replete media the vegetative cells of the mutant are more cylindrical acid have thicker septa than those of the wild type, while in nitrogen-free media the mutant heterocysts lack the normal glycolipid layer external to the cell wall. Although this layer is absent, strain 543 heterocysts nevertheless contain heterocyst-specific glycolipids, as determined by thin-layer chromatography. The mutation in strain 543 is in a gene we have named hglK, encoding a protein of 727 amino acids. The wild-type HglK protein appears to contain four membrane-spanning regions followed by 36 repeats of a degenerate pentapeptide sequence, AXLXX. The mutation in strain 543 introduces a termination codon immediately upstream of the pentapeptide repeat region. A mutant constructed by insertion of an antibiotic resistance cassette near the beginning of the hglK gene has the same phenotype as strain 543. We propose that hglK encodes a protein necessary for the localization of heterocyst glycolipids and that this function requires the pentapeptide repeats of the HglK protein.
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页码:6440 / 6448
页数:9
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