RNA-seq reveals the critical role of CspA in regulating Brucella melitensis metabolism and virulence.

Zhen Wang,Pengfei Bie,Wenxiao Liu,Tonglei Wu,Qingmin Wu

doi:10.1007/s11427-015-4981-6

Abstract

Brucella melitensis is a facultative intracellular bacterium that replicates within macrophages. The ability of Brucella to survive and multiply in the hostile environment of host macrophages is essential for its virulence. The cold shock protein CspA plays an important role in the virulence of B. melitensis. To analyze the genes regulated by CspA, the whole transcriptomes of B. melitensis NIΔcspA and its parental wild-type strain, B. melitensis NI, were sequenced and analyzed using the Solexa/Illumina sequencing platform. A total of 446 differentially expressed genes were identified, including 324 up-regulated and 122 down-regulated genes. Numerous genes identified are involved in amino acid, fatty acid, nitrogen, and energy metabolism. Interestingly, all genes involved in the type IV secretion system and LuxR-type regulatory protein VjbR were significantly down-regulated in NIΔcspA. In addition, an effector translocation assay confirmed that the function of T4SS in NIΔcspA is influenced by deletion of the cspA gene. These results revealed the differential phenomena associated with virulence and metabolism in NIΔcspA and NI, providing important information for understanding detailed CspA-regulated interaction networks and Brucella pathogenesis.

Highlights

Brucella melitensis is a facultative intracellular pathogen that resides and replicates within specialized compartments of macrophages (Martirosyan et al, 2011)
After quality evaluation using FastQC, the clean reads were matched to the genome of B. melitensis NI using the alignment program Short Oligonucleotide Analysis Package (SOAP)
Statistical analysis revealed a total of 446 genes that were differentially expressed in NI cspA versus in B. melitensis NI

Summary

Introduction

Brucella melitensis is a facultative intracellular pathogen that resides and replicates within specialized compartments of macrophages (Martirosyan et al, 2011). Matics (He, 2012), which include lipopolysaccharide (Seleem et al, 2008), the type IV secretion system T4SS (Seleem et al, 2008; Martirosyan et al, 2011), the quorum-sensing-related transcriptional regulator VjbR (Delrue et al, 2005), the BvrR/BvrS two-component regulatory system (Sola-Landa et al, 1998; Martinez-Nunez et al., 2010), and the periplasmic cyclic -1,2 glucans (Briones et al, 2001), among others Most of these genes are not direct virulence factors, but are transcription regulators, such as VjbR which can control the expression of virulence factors to affect Brucella virulence (Delrue et al, 2005). Novel transcription regulators and regulatory RNAs related to the virulence of Brucella were recently identified, including MucR (Dong et al, 2013; Mirabella et al, 2013), GntR (Haine et al, 2005), NnrA (Haine et al, 2006), Wang, Z., et al Sci China Life Sci April (2016) Vol. No.4

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