AbaM Regulates Quorum Sensing, Biofilm Formation, and Virulence in <i>Acinetobacter baumannii</i>

ABSTRACT Acinetobacter baumannii possesses a single divergent luxR / luxRI -type quorum-sensing (QS) locus named abaR abaI . This also contains third gene located between and , which we term abaM that codes for an uncharacterized member of the RsaM protein family known to regulate N -acylhomoserine lactone (AHL)-dependent QS in other beta- gammaproteobacteria. Here, show disruption via T26 insertion A. strain AB5075 resulted increased production -(3-hydroxydodecanoyl)- l -homoserine enhanced surface motility biofilm formation. In contrast wild type ::T26 mutant, virulence mutant was completely attenuated Galleria mellonella infection model. Transcriptomic analysis revealed AbaM differentially regulates at least 76 genes, including csu pilus operon acinetin 505 lipopeptide biosynthetic operon, are involved adherence, formation virulence. A comparison type, transcriptomes, indicates ?21% regulon operon. Moreover, genes ( ) were among most upregulated mutant. lux -based reporter fusions expression is positively regulated by but negatively autoregulated. Overall, data presented this work demonstrates plays central role regulating QS, virulence, motility, IMPORTANCE multiantibiotic-resistant pathogen global health care importance. Understanding regulation could aid development novel anti-infective strategies. code receptor synthase components (AHL) lactone-dependent quorum sensing system separated although mutation AHL production, development, it attenuation found control both QS-dependent QS-independent genes. The significance lies identification AbaM, ortholog plant pathogens, as modulator human pathogen.