Inactivation of AdeABC and AdeIJK efflux pumps elicits specific non-overlapping transcriptional and phenotypic responses in Acinetobacter baumannii

Purpose: In this study, we analyzed the contributions of AdeABC and AdeIJK in antibiotic resistance and growth physiology of the two MDR strains, AYE and AB5075. Methods: To further characterize the functional interactions between AdeABC and AdeIJK, we carried out RNAseq analysis of the exponential AB5075 and its single and double efflux knockout cells. High quality total RNA was further processed by removing 23S and 16S rRNAs using the MicrobExpress bacterial mRNA enrichment kit. Samples were analyzed in duplicate using Illumina MiSeq. Raw data for each sample was analyzed using CLC Genomics Workbench version 12.0.1 software (QIAGEN Aarhus, Denmark). Results: Our results suggest that inactivation of AdeIJK elicits broader changes in the abundances of mRNAs and this response is modified in the absence of AdeB. In contrast, inactivation of AdeB leads to a focused cellular response, which is not sensitive to the activity of AdeIJK. We identified additional efflux pumps and transcriptional regulators that contribute to MDR phenotype of clinical A. baumannii isolates. Conclusion: Our results suggest that inactivation of AdeIJK elicits broader changes in the abundances of mRNAs and this response is modified in the absence of AdeB. In contrast, inactivation of AdeB leads to a focused cellular response, which is not sensitive to the activity of AdeIJK. RNAseq analysis of the exponential AB5075 and its single and double efflux knockout cells (parent, adeB::T26, ΔadeIJK, adeB::T26 ΔadeIJK); 4 samples in duplicate