The hglK gene is required for localization of heterocyst-specific glycolipids in the cyanobacterium Anabaena sp. strain PCC 7120.

AUTOR(ES)

Black, K

RESUMO

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 and 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.

Documentos Relacionados

• Heterocyst-Specific Expression of patB, a Gene Required for Nitrogen Fixation in Anabaena sp. Strain PCC 7120
• Two Anabaena sp. strain PCC 7120 DNA-binding factors interact with vegetative cell- and heterocyst-specific genes.
• Nitrate assimilation gene cluster from the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120.
• Protein tyrosine phosphorylation in the cyanobacterium Anabaena sp. strain PCC 7120.
• Physical and genetic maps of the genome of the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120.