Mutations in genes patA and patL of Anabaena sp. strain PCC 7120 result in similar phenotypes, and the proteins encoded by those genes may interact

Abstract

PatA resembles a response regulator protein with a defective DNA-binding domain, and PatL (All3305) is a pentapeptide repeat protein. A yeast two-hybrid library identified PatL as a protein with which PatA may interact. Heterocysts of patA and patL Anabaena sp. form nearly exclusively terminally in long filaments, further linking the genes.

Fig. 1.

(a) Wild-type Anabaena sp. has semiregularly spaced heterocysts. (b) In contrast, the all3305 (patL) mutant DR3304b forms heterocysts almost exclusively at the end(s) of the filaments, a phenotype resembling that of a patA mutant (29). Heterocysts are stained with Alcian blue.

Fig. 2.

Pentapeptide repeat region of All3305. The 45 pentapeptide repeats of the 496-amino-acid predicted protein All3305 near its C terminus are largely [A₃₅/C₄/V₄][N₂₄/D₆/K₅] [L₃₇/F₅][X][G₂₀/X]. Amino acid numbers are shown.