| Project ID |
BITS-SRIP/028EE9/2026 |
| Project Title |
Role of CpxR-CpxA in regulation of Type VI Secretion System in Enterobacter cloacae |
| Project Description |
Enterobacter cloacae, a member of the ESKAPE pathogens, group of multidrug-resistant nosocomial pathogens. E. cloacae are increasingly recognised as a cause of bloodstream, respiratory, urinary tract and device-associated infections in healthcare settings, particularly in immunocompromised or critically ill patients. It employs a combination of strategies to persist in clinical environments, including intrinsic and acquired antibiotic resistance, biofilm formation on both biotic and abiotic surfaces, the production of toxins and adhesins, and the use of a specialised secretion system to interact with host tissue and competing microbes. Among the virulence determinants, the Type 6 secretion system (T6SS) has gained more attention as an envelope-spanning contractile nanomachine that injects effectors into neighbouring cells. Its structure is homologous to an inverted bacteriophage tail, composed of a membrane complex, baseplate, sheath and tube, distal end. Studies have shown that E. cloacae harbours two T6SS clusters that promote adherence, biofilm formation, colonisation and interbacterial killing, suggesting that it is the main contributor to its fitness and pathogenic potential.
Studies in other Gram-negative bacteria have demonstrated that the T6SS is regulated at the transcriptional, post-transcriptional, and post-translational levels through various mechanisms. It is even regulated by both biotic and abiotic factors. One of the major mechanisms for this integration is provided by two-component systems (TCSs). TCS, comprising a histidine kinase and a response regulator, detects cues such as osmolarity, pH, or envelope stress and adjusts T6SS gene expression accordingly, ensuring that T6SS assembly and firing occur when they confer a selective advantage. There are multiple reports indicating that environmental cues activate the two-component system, which regulates the expression of the T6SS. In acidic conditions, TCS ChvG/ChvI of Agrobacterium tumefaciens induces T6SS expression. In Klebsiella pneumoniae, locus I of T6SS is regulated by TCS PhoP/PhoQ, activated by ROS and antibiotics. Under osmotic stress, the T6SS of Yersinia pseudotuberculosis is regulated by the TCS EnvZ/OmpR. T6SS of Pseudomonas aeruginosa is regulated by TCS GacS/GacA and FleS/FleR. T6SS of E. cloacae is regulated by quorum sensing. T6SS of members of the Enterobacteriaceae family is regulated by TCS, but till now, there are no studies that show that the T6SS of E. cloacae is regulated by TCS. This raises a question: Is there any TCS involved in the regulation of the T6SS of E. cloacae?
To determine this, bioinformatics studies were conducted to identify all the TCS present in E. cloacae. Operons of both clusters of T6SS were identified, and motifs in each operon were identified. Motifs were compared to find any TCS; they showed similarity with motifs of some TCS. One of which is CpxR, a two-component response regulator. In avian pathogenic E. coli, CpxR regulates T6SS-2. This suggests that the T6SS of E. cloacae may be regulated by the TCS CpxA/CpxR. The aim of this study is to investigate the role of CpxR in controlling the expression and activity of the T6SS of E. cloacae. Elucidating this regulatory link will provide insight into how an ESKAPE pathogen integrates envelope stress responses with interbacterial warfare and virulence, and may reveal new targets for attenuating its pathogenic potential. Therefore, the present study aims to elucidate role of CpxR-CpxA TCS in regulation of T6SS. One of the objective of this work is cloning and purification of CpxR protein. The candidate will learn various molecular biology methods for cloning of CpxR which includes primer designing, PCR, restriction digestion, ligation, transformation, expression studies and purification etc. A student with some knowledge of Microbiology and Molecular Biology will be preferred. |
| Project Discipline |
Life science and allied disciplines like Microbiology, Biotechnology etc. |
| Faculty Name |
Prabhat Nath Jha |
| Department |
Department of Biological Sciences |
