title: Molecular mechanisms of ethanol-induced pathogenesis revealed by RNA-sequencing.
abstract: Acinetobacter baumannii is a common pathogen whose recent resistance to drugs has emerged as a major health problem. Ethanol has been found to increase the virulence of A. baumannii in Dictyostelium discoideum and Caenorhabditis elegans models of infection. To better understand the causes of this effect, we examined the transcriptional profile of A. baumannii grown in the presence or absence of ethanol using RNA-Seq. Using the Illumina/Solexa platform, a total of 43,453,960 reads (35 nt) were obtained, of which 3,596,474 mapped uniquely to the genome. Our analysis revealed that ethanol induces the expression of 49 genes that belong to different functional categories. A strong induction was observed for genes encoding metabolic enzymes, indicating that ethanol is efficiently assimilated. In addition, we detected the induction of genes encoding stress proteins, including upsA, hsp90, groEL and lon as well as permeases, efflux pumps and a secreted phospholipase C. In stationary phase, ethanol strongly induced several genes involved with iron assimilation and a high-affinity phosphate transport system, indicating that A. baumannii makes a better use of the iron and phosphate resources in the medium when ethanol is used as a carbon source. To evaluate the role of phospholipase C (Plc1) in virulence, we generated and analyzed a deletion mutant for plc1. This strain exhibits a modest, but reproducible, reduction in the cytotoxic effect caused by A. baumannii on epithelial cells, suggesting that phospholipase C is important for virulence. Overall, our results indicate the power of applying RNA-Seq to identify key modulators of bacterial pathogenesis. We suggest that the effect of ethanol on the virulence of A. baumannii is multifactorial and includes a general stress response and other specific components such as phospholipase C.
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut, United States of America.
authors.forename: Laura
authors.initials: L
authors.lastname: Camarena
authors.forename: Vincent
authors.initials: V
authors.lastname: Bruno
authors.forename: Ghia
authors.initials: G
authors.lastname: Euskirchen
authors.forename: Sebastian
authors.initials: S
authors.lastname: Poggio
authors.forename: Michael
authors.initials: M
authors.lastname: Snyder
mesh_terms: D000151:Acinetobacter Infections / Q000378:metabolism / Q000473:pathology; D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000235:genetics / Q000472:pathogenicity*; D002460:Cell Line; D002492:Central Nervous System Depressants / Q000494:pharmacology*; D000431:Ethanol / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects*; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects / Q000235:genetics; D006801:Humans; D012329:RNA, Bacterial / Q000032:analysis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D010738:Type C Phospholipases / Q000096:biosynthesis / Q000187:drug effects; D014774:Virulence / Q000187:drug effects / Q000235:genetics
chemical_list: D002492:Central Nervous System Depressants; D012329:RNA, Bacterial; D000431:Ethanol; D010738:Type C Phospholipases