Mutants of the hybrid sensor kinase CstA affect cyst cell development in Azospirillum brasilense Sp7

摘要

We previously characterized a gene (originally named?org35, renamed?cstA)?encoding aPAS/PAC sensor hybrid histidine?kinase?(HK)?which interacts with?Azospirilum brasilenseNifA in a yeast two-hybrid system.?The predicted CstA is a hybrid sensor kinase, comprising two N-terminal PAS domains, a?histidine?kinase?core domain and a?response regulator receiver (RR)?domain. To determine the function of the?cstA, two mutants wereconstructed including two in-frame deletion mutants?ΔHK?and?ΔRR. A microscopic analysis revealed that?both?cstA?mutants?developed mature cyst cells more quickly than the wild type.?Moreover,?cstA?mutants are affected in colony morphology?which are essential for?A.?brasilense?cells to differentiate into cyst-like forms. These observations suggested that?cstA?is involved in cyst development in?A. brasilense.