Characterization of the sensor domain of QseE histidine kinase from Escherichia coli
Introduction
Quorum sensing is also cell-to-cell communication in bacteria. It is a critical process for cell survival as it protects the cells from external environment through biofilm formation, virulence, and antibiotic resistance [1], [2], [3]. In this process, there is sensing of small molecules, such as oligopeptides in Gram-positive bacteria; AI-1 (autoinduer-1) and AI-2 (autoinducer-2), which are N-Acyl Homoserine Lactones (AHL) found in both Gram-negative and Gram-positive bacteria; and AI-3 (autoinducer-3) in Gram-negative bacteria [1]. AI-1 is synthesized by LuxI and released into the surrounding environment. When the population density of bacteria is high, the local concentration of AI-1 increases in the environment. Consequently, AI-1 diffuses into the cell. Then, LuxR easily senses AI-1 in the cell and activates the luciferase operon [4], [5], [6]. In Escherichia coli and Salmonella typhimurium, AI-2 is created from LuxS-derived 4,5-dihydroxy-2,3-pentanedione (DPD). Then, it is imported into the cell by LsrABC transporters. Finally, it is phosphorylated by LsrK. The phosphorylated AI-2 interacts with the transcriptional repressor, LsrR, which activates lsr operon [7]. In Vibrio spp, AI-2 (a furanosyl borate diester) binds with LuxP in the periplasm: the resultant complex interacts with the histidine kinase LuxQ. Consequently, there is phosphorylation of conserved histidine of LuxQ. The phosphate group is transferred to the response regulator LuxO via the LuxQ/LuxO phoshporyl cascade [1]. Recently, it has been proved that QseBC and QseFE are the two component systems that are involved in bacterial quorum sensing and regulation of virulence factors in pathogenic bacteria, such as enterohemorrhagic E. coli (EHEC) O157:H7 and salmonella enterica serovar Typhimurium [8], [9], [10], [11], [12]. QseC HK senses the auto inducer 3 (AI-3), epinephrine, and norepinephrine of host hormones. Its cognate response regulator QseB regulates virulence factors, including the locus of enterocyte effacement (LEE) genes; these genes cause intestinal colonization by stimulating the formation of ‘attaching and effacing’ (AE) lesions, flagellar, and motility genes [13]. The sensor domain of QseE not only senses epinephrine hormone but also phosphate and sulfate ions. Thereafter, it activates its response regulator QseF [9], [10], [12], which subsequently regulates the transcription of virulence factor genes, such as sipA and sopB genes; these genes are involved in the invasion of epithelial cells and espFu gene, driving the polymerization of actin during AE lesion formation [11], [12]. This indicates that the sensor domains of QseC and QseE may be antimicrobial drug targets that block bacterial quorum sensing and virulence factors [14]. Recently, we have successfully elucidated the structural characteristics of the sensor domain of QseC in solution state [15]. In this study, we produced and characterized the sensor domain of QseE of E. coli K12 strain, which has 99% sequence identity from that of EHEC O157:H7 strain. Thus, this study provides a foundation for structural and functional studies that focus on the sensor domains of QseE histidine kinases.
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Cloning and expression of the sensor domain of QseE
The DNA sequence of the sensor domain of QseE (resiudes Q35-Q173) was amplified from genomic DNA of E. coli K12 using the polymerase chain reaction (PCR): 5′-CGCCATATGCAAAGCCTGAATGCGCTTAGCG-3′ was used as the forward primer, while 5′-CGCCTCGAGTCATTGCCCACGTTCGGCGATTTCA-3′ was used as the reverse primer. The PCR fragment was cloned into pET28a (+) vector using T4 ligase and the restriction enzymes: Nde I and Xho I. The plasmid encoded the QseE sensor domain, including 6×His-tag at its N-terminus;
Domain organization of QseE and secondary structure prediction of its sensor domain
Domain analysis was conducted using SMART (Simple Modular Architecture Research Tool) service. The results of domain analysis indicated that full length QseE consists of a periplasmic sensor domain (residues 35–174) and a kinase domain. The periplasmic sensor domain is located between two transmembrane helices (residues 15–34 and 175–197), while the kinase domain is composed of two subdomains (His Kinase A (phosphoacceptor) domain and ATP binding CA domain) (Fig. 1A). The secondary structure
Discussion
In pathogenic bacteria, cell-to-cell communication occurs through the recognition of signaling molecules in the host environment; this communication is essential for regulating the virulence factors of bacteria. In particular, QseBC and QseFE are the two component systems that sense host hormones: epinephrine and/or norepinephrine. Furthermore, QseBC and QseFE regulate the expression of virulence genes in pathogenic bacteria, such as EHEC and Salmonella enterica serovar Typhimurium [9], [10],
Acknowledgments
This research was supported by a Korea University Grant and the National Research Foundation of Korea (NRF) grant funded by the Korea government(Ministry of Science, ICT and Future Planning) (No. NRF-2014M3A9D9069710, NRF-2013M3A6A4045160, and NRF-2014R1A4A1007304). KYH was supported by KU grants.
References (18)
- et al.
Bacterial bioluminescence: isolation and genetic analysis of functions from Vibrio fischeri
Cell
(1983) - et al.
Mg2-induced folding of the sensor domain of QseC histidine kinase from enterohemorrhagic Escherichia coli (EHEC) O157:H7
Process Biochem.
(2014) - et al.
Sensor domains of two-component regulatory systems
Curr. Opin. Microbiol.
(2010) - et al.
Structural characterization of the predominant family of histidine kinase sensor domains
J. Mol. Biol.
(2010) - et al.
Cell-to-cell signalling during pathogenesis
Cell. Microbiol.
(2009) - et al.
Quorum sensing: cell-to-cell communication in bacteria
Annu. Rev. Cell. Dev. Biol.
(2005) - et al.
Quorum sensing in bacteria
Annu. Rev. Microbiol.
(2001) - et al.
Identification of genes and gene products necessary for bacterial bioluminescence
Proc. Natl. Acad. Sci. U. S. A.
(1984) - et al.
Identification of the operator of the lux regulon from the Vibrio fischeri strain ATCC7744
Proc. Natl. Acad. Sci. U. S. A.
(1989)
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