Mutation of an alternative sigma factor in the cyanobacterium nostoc punctiforme results in increased infection of its symbiotic plant partner, anthoceros punctatus

Abstract

An alternative group 2 sigma factor was identified in the nitrogen- fixing, symbiotically competent cyanobacterium Nostoc punctiforme and designated sigH. Transcription of sigh was specifically induced within 1.5 h following exposure of N. punctiforme to its symbiotic plant partner, Anthoceros punctatus. A mutation in sigh resulted in a sixfold-higher initial infection of A. punctatus tissue without a parallel increase in nitrogen- fixing activity.