Cellular Responses during Morphological Transformation in Azospirillum brasilense and Its flcA Knockout Mutant: e114435

• Published in: PloS one 2014-12, Vol.9 (12)
• Main Authors: Hou, Xingsheng, McMillan, Mary, Coumans, Joeelle VF, Poljak, Anne, Raftery, Mark J, Pereg, Lily
• Format: Article
• Language: English
• Subjects: Azospirillum; Azospirillum brasilense
• ISSN: 1932-6203
• DOI: 10.1371/journal.pone.0114435

FlcA is a response regulator controlling flocculation and the morphological transformation of Azospirillum cells from vegetative to cyst-like forms. To understand the cellular responses of Azospirillum to conditions that cause morphological transformation, proteins differentially expressed under flocculation conditions in A. brasilense Sp7 and its flcA knockout mutant were investigated. Comparison of 2-DE protein profiles of wild-type (Sp7) and a flcA deletion mutant (Sp7-flcA Delta ) revealed a total of 33 differentially expressed 2-DE gel spots, with 22 of these spots confidently separated to allow protein identification. Analysis of these spots by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and MASCOT database searching identified 48 proteins ( greater than or equal to 10% emPAI in each spot). The functional characteristics of these proteins included carbon metabolism (beta-ketothiolase and citrate synthase), nitrogen metabolism (Glutamine synthetase and nitric oxide synthase), stress tolerance (superoxide dismutase, Alkyl hydroperoxidase and ATP-dependent Clp protease proteolytic subunit) and morphological transformation (transducer coupling protein). The observed differences between Sp7 wild-type and flcA- strains enhance our understanding of the morphological transformation process and help to explain previous phenotypical observations. This work is a step forward in connecting the Azospirillum phenome and genome.