title: Cag type IV secretion system: CagI independent bacterial surface localization of CagA.
abstract: Helicobacter pylori Cag type IV secretion system (Cag-T4SS) is a multi-component transporter of oncoprotein CagA across the bacterial membranes into the host epithelial cells. To understand the role of unique Cag-T4SS component CagI in CagA translocation, we have characterized it by biochemical and microscopic approaches. We observed that CagI is a predominantly membrane attached periplasmic protein partially exposed to the bacterial surface especially on the pili. The association of the protein with membrane appeared to be loose as it could be easily recovered in soluble fraction. We documented that the stability of the protein is dependent on several key components of the secretion system and it has multiple interacting partners including a non-cag-PAI protein HP1489. Translocation of CagA across the bacterial membranes to cell surface is CagI-independent process. The observations made herein are expected to assist in providing an insight into the substrate translocation by the Cag-T4SS system and Helicobacter pylori pathogenesis.
authors.affiliation: Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Navin
authors.initials: N
authors.lastname: Kumar
authors.forename: Mohd
authors.initials: M
authors.lastname: Shariq
authors.forename: Rajesh
authors.initials: R
authors.lastname: Kumari
authors.forename: Rakesh K
authors.initials: RK
authors.lastname: Tyagi
authors.forename: Gauranga
authors.initials: G
authors.lastname: Mukhopadhyay
mesh_terms: D000942:Antigens, Bacterial / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D058947:Bacterial Secretion Systems; D003001:Cloning, Molecular; D010861:Fimbriae, Bacterial / Q000378:metabolism; D016480:Helicobacter pylori / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism*; D009154:Mutation; D019897:Periplasm / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C080866:cagA protein, Helicobacter pylori
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