Campylobacter jejuni Gene Expression in the Chick Cecum: Evidence for Adaptation to a Low-Oxygen Environment

Abstract

Transcriptional profiling of Campylobacter jejuni during colonization of the chick cecum identified 59 genes that were differentially expressed in vivo compared with the genes in vitro. The data suggest that C. jejuni regulates electron transport and central metabolic pathways to alter its physiological state during establishment in the chick cecum

CmeR Functions as a Pleiotropic Regulator and Is Required for Optimal Colonization of Campylobacter jejuni In Vivo

“…2 and 3). This regulatory feature is similar to that of CmeABC (21,22) and is consistent with the findings of other investigators that Cj0561c and cmeABC are upregulated in the intestinal tract (40,47), where bile compounds are present. Although CmeR is the primary factor controlling the expression of Cj0561c, the transcription of Cj0561c was further induced by bile salts in the CmeR-negative background (Fig.…”

“…Subsequent tests using realtime qRT-PCR confirmed that cmeA (10-fold) and cmeC (15-fold) were also upregulated in 11168⌬cmeR. The lack of simultaneous detection of all genes in an affected operon by the DNA microarray has also been observed in other studies (40,47) and suggests that DNA microarray analysis has a lower sensitivity than real-time qRT-PCR. Interestingly, Cj0583 showed a 6.6-fold change in expression when the DNA microarray was used, but this was not verified by real-time RT-PCR (Table 3).…”

“…It was also speculated by Sellars et al (37) that the reduction of DMSO and TMAO facilitates Campylobacter survival outside the host, such as in aquatic environments. Notably, aspA, dcuA, dcuB, and sdhA were shown by Woodall et al (47) to be substantially upregulated in the chicken cecum, suggesting that they are involved in Campylobacter adaptation to the environment in the gut. At this stage, it is not known if CmeR directly or indirectly regulates the C 4 -dicarboxylate transport and utilization system and if the Dcu system is regulated by multiple mechanisms.…”

“…Once transported into the cytoplasm, aspartate is converted to fumarate by aspartase (encoded by aspA). When oxygen is limited or absent, fumarate can be used as an alternative terminal electron acceptor in the electron transport chain and supports Campylobacter growth under such conditions (19,37,47). DcuB is predicted to function as a transporter for C 4 -dicarboxylates (succinate and fumarate), exchanging succinate for fumarate, which serves as a terminal electron acceptor (37).…”

Campylobacter jejuni proteins Cj0952c and Cj0951c affect chemotactic behaviour towards formic acid and are important for invasion of host cells

“…In contrast, in strains 81-176 and 81116, the corresponding chemoreceptor is encoded by a single gene that encompasses the MCP domain, the transmembrane domain as well as the signalling domain. So far, cj0952c has only been described to be upregulated during colonization of the chick caecum (Woodall et al, 2005), although not with regard to its biological function. As for many other bacteria, C. jejuni possesses genes essential for chemotaxis, such as cheA, chew, cheY and MCP receptors.…”