Project description:A. baumannii has the propensity to colonize abiotic surfaces and this is thought to mediate its transmission to susceptible patients. We found that disruption of A. baumannii ribonuclease T2 family protein (ATCC 17978 locus A1S_3026) severely diminishes the organism's ability to colonize abiotic surfaces. We used Affymetrix A. baumannii GeneChips (part number PMDACBA1) to compare the gene expression properties of wild type and isogenic ribonuclease T2 family protein mutant cells.
Project description:A. baumannii has the propensity to colonize abiotic surfaces and this is thought to mediate its transmission to susceptible patients. We found that disruption of A. baumannii ribonuclease T2 family protein (ATCC 17978 locus A1S_3026) severely diminishes the organism's ability to colonize abiotic surfaces. We used Affymetrix A. baumannii GeneChips (part number PMDACBA1) to compare the gene expression properties of wild type and isogenic ribonuclease T2 family protein mutant cells. A. baumanni strain 98-37-09 (wild type) or isogenic ACJ7 (harboring a EZ-Tn5 insertion in A1S_3026) cells were grown to mid-exponential phase growth in Luria Burtani medium, total bacterial RNA was isolated and subjected to GeneChip hybridization and analysis. We sought to determine the regulatory effects of A1S_3026.
Project description:Acinetobacter baumannii A1S_1874 gene encodes as a LysR-type transcriptional regulator. LysR family regulators known to regulate biofilm formation, antibiotic resistance, and the expression of diverse genes in other Gram-negative bacteria. However, A1S-1874 has never been characterized in Acinetobacter baumannii, and the studies about the regulon of A1S-1874 are not discovered. In this study we revealed that A1S_1874 differentially regulates at least 302 genes including the csu pilus operon, N-acylhomoserine lactone synthese gene, A1S_0112-A1S_0118 operon, type 1v secretion system related genes that are involved in biofilm formation, surface motility, adherence, quorum sensing and virulence. Overall, our data suggests that A1S-1874 is a key regulator of Acinetobacter baumannii biofilm formation and gene expression.
Project description:Acinetobacter baumannii possesses a single divergent luxR/luxI-type quorum sensing (QS) locus named abaR/abaI. This locus also contains a third gene located between abaR and abaI which we term abaM that codes for an uncharacterized member of the RsaM protein family known to regulate N-acylhomoserine lactone (AHL) dependent QS and the expression of diverse genes in other β- and γ-proteobacteria. However, abaM has never been charatcerized in Acinetobacter baumannii, and the studies about the regulon of abaI are limited. In this study we revealed that AbaM differentially regulates at least 76 genes including the csu pilus operon and the acinetin 505 lipopeptide biosynthetic operon, that are involved in surface adherence, biofilm formation and virulence. A comparison of the wild type, abaM::Tn26 and abaI::Tn26 transcriptomes, indicates that AbaM regulates ~21% of the QS regulon including the csu operon. Moreover, the QS genes (abaI/abaR) were among the most upregulated in the abaM::Tn26 mutant. Overall, our data suggests that abaM is a key regulator of Acinetobacter baumannii QS and gene expression.
Project description:The long-term resistance to desiccation on abiotic surfaces is a key determinant of the adaptive success of Acinetobacter baumannii as a healthcare-associated bacterial pathogen. Here, the cellular and molecular mechanisms enabling A. baumannii to resist desiccation and persist on abiotic surfaces were investigated. Experiments were set up to mimic the A. baumannii response to air-drying that would occur when bacterial cells contaminate fomites in hospitals. Resistance to desiccation and transition to the “viable but nonculturable” (VBNC) state were determined in the laboratory-adapted strain ATCC 19606T and the epidemic strain ACICU. Culturability, membrane integrity, metabolic activity, virulence, and gene expression profile were compared between the two strains at different stages of desiccation. Upon desiccation, ATCC 19606T and ACICU cells lose culturability and membrane integrity, lower their metabolism, and enter the VBNC state. However, desiccated A. baumannii cells fully recover culturability and virulence in an insect infection model following rehydration in physiological buffers or human biological fluids. Transcriptome and chemical analyses of A. baumannii cells during desiccation unveiled the production of protective metabolites (L-cysteine and L-glutamate) and decreased energetic metabolism consequent to activation of the glyoxylate shunt (GS) pathway, as confirmed by reduced resuscitation efficiency of aceA mutants, lacking the key enzyme of the GS pathway. VBNC cell formation and extensive metabolic reprogramming provide a biological basis for the response of A. baumannii to desiccation, with implications on environmental control measures aimed at preventing the transmission of A. baumannii infection in hospitals.
Project description:The experiment contains ChIP-seq data for Acinetobacter baumannii strain AB5075 encoding 3xFLAG tagged H-NS. Experiments were done with or without ectopic expression of the truncated H-NS-39 protein (corresponding to the H-NS multimerization surface). The strain was grown at 37 degrees in LB medium and crosslinked with 1 % (v/v) formaldehyde. After sonication, to break open cells and fragment DNA, immunoprecipitations were done using anti-FLAG antibodies against. Libraries were prepared using DNA remaining after immunoprecipitation.
Project description:A major reservoir for spread of the emerging pathogen Acinetobacter baumannii is hopsital surfaces, where bacteria persist in a desiccated state. To identify gene products influencing desiccation survival, a transposon sequencing (Tn-seq) screen was performed. Using this approach, we identified genes both positively and negatively impacting the desiccation tolerance of A. baumannii.
Project description:Acinetobacter baumannii is a major cause of nosocomial infections which can survive in different hospital environments and its multidrug-resistant capacity is major concern now-a-days. ppGpp dependent stringent response mediates reprogramming of gene expression with diverse function in many bacteria. A baumannii A1S_0579 gene is responsible for ppGpp production. Transcriptome analysis of early stationary phase cultures represents several differentially expressed genes in ppGpp deficient strain (∆A1S_0579). We found that the expression of csu operon, which is important in pili biosynthesis for early biofilm formation, was significantly reduced in the ppGpp-deficient strain. Our findings showed that ppGpp signaling plays critical role in biofilm formation, surface motility, adherence and virulence of A baumannii. This study is the first demonstration of the association between ppGpp and pathogenicity of A. baumannii.