Paired cysteine residues are required for high levels of the Helicobacter pylori autotransporter VacA.
The Helicobacter pylori vacuolating cytotoxin VacA shares homology in its C-terminal domain with many autotransporter proteins, suggesting a similar mechanism of secretion. Like most autotransporters, VacA contains a single pair of cysteine residues located near the C-terminus of the passenger domain. This study aimed to investigate the role of these conserved cysteine residues. This involved changing each cysteine in the VacA passenger domain to serine, quantifying the effect on VacA levels and assessing toxin activity in H. pylori. It was shown that both cysteine residues were required for high VacA levels, although mutation of each cysteine reduced toxin amounts to differing extents, implying that their importance was not simply for intramolecular disulphide bond formation. Although less VacA was observed for the cysteine mutants, vacuolating activity was detected, showing that the cysteines were not required for VacA function.
Letley
Darren P
DP
Institute of Infection, Immunity and Inflammation, University of Nottingham, Queen's Medical Centre, Clifton Boulevard, Nottingham NG7 2UH, UK.|Wolfson Digestive Diseases Centre, University of Nottingham, Queen's Medical Centre, Clifton Boulevard, Nottingham NG7 2UH, UK.
Rhead
Joanne L
JL
Institute of Infection, Immunity and Inflammation, University of Nottingham, Queen's Medical Centre, Clifton Boulevard, Nottingham NG7 2UH, UK.|Wolfson Digestive Diseases Centre, University of Nottingham, Queen's Medical Centre, Clifton Boulevard, Nottingham NG7 2UH, UK.
Bishop
Keith
K
Institute of Infection, Immunity and Inflammation, University of Nottingham, Queen's Medical Centre, Clifton Boulevard, Nottingham NG7 2UH, UK.
Atherton
John C
JC
Institute of Infection, Immunity and Inflammation, University of Nottingham, Queen's Medical Centre, Clifton Boulevard, Nottingham NG7 2UH, UK.|Wolfson Digestive Diseases Centre, University of Nottingham, Queen's Medical Centre, Clifton Boulevard, Nottingham NG7 2UH, UK.
D019943:Amino Acid Substitution; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000633:toxicity; D002460:Cell Line; D003545:Cysteine / Q000235:genetics / Q000502:physiology*; D006367:HeLa Cells; D016480:Helicobacter pylori / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D006801:Humans; D008853:Microscopy; D016297:Mutagenesis, Site-Directed; D011817:Rabbits
D001426:Bacterial Proteins; C074689:VacA protein, Helicobacter pylori; D003545:Cysteine