Transcription profiling of E. coli NMB0419 mutants to investigate the role of this tetratricopeptide-repeats-encoding gene in bacterial adherence to human epithelial cells

ABSTRACT: The gene NMB0419 of Neisseria meningitidis strain MC58 encodes a putative tetratricopeptide repeats (TPR) containing protein, which was implicated in respiratory epithelial invasion. We have accordingly sought a role for NMB0419 in meningococcal adherence and invasion of human epithelial cells using Escherichia coli surrogates. In trans expression of NMB0419 promoted adherence of the E. coli strain to human epithelial cells, which showed a unique aggregative adherence pattern that was observed for pathogenic E. coli. This adherence was totally abolished by addition of D-mannose, suggesting that formation of type 1 pili on the surface of E. coli strain was solely responsible for the adherence and was facilitated by the expression of NMB0419. This was further supported by rigid pilus structures seen on the surface of NMB0419 expressing E. coli using electron microscopy. A survey of other meningococcal strains including serogroup A, B, C, W, X, Y and Z (n=3, 42, 10, 1, 1, 1, and 1, respectively) revealed that an NMB0419 homologue was present in all strains, however, encoded varying number of TPR domains from 1 to 7. E. coli with in trans expression of such a homologue (NMA2065) encoding single TPR domain also showed enhanced adherence to the level that was observed for the E. coli strain expressing NMB0419 encoding for 4 TPR domains. Nevertheless, in-frame deletion of the TPR-domain coding sequence from the expression plasmid construct reduced the E. coli adherence to the background level. Revisit of the NMB0419 mutant strain of meningococcus indicated that reduction in adherence was primarily responsible for the reduced epithelial invasion that was previously observed. Study of transcriptome profiles in E. coli using microarray showed that the most significantly up-regulated genes in NMB0419 expressing E. coli belonging to the fim operon encoding all necessary structure proteins and chaperons for type 1 pili, strongly suggesting a gene regulatory role for NMB0419. Although the mechanism yet to be explored, this is the first study to showed that TPR domains are involved in bacterial adherence and that a gene encoding single functional TPR domain produced the same phenotype as a homologue encoding multiple TPR domains did.

ORGANISM(S): Escherichia coli

SUBMITTER: Ming-Shi Li 

PROVIDER: E-MEXP-2485 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress