microbiology, Vol 140, 1755-1761, Copyright © 1994 by Society for General Microbiology
A new extracellular protein of Pseudomonas aeruginosa PA103 regulated by regA
C Wolz, R Lehmann, ML Vasil, R Bischoff and G Doring
Department of General and Environmental Hygiene, University of Tubingen, Germany.
The expression of exotoxin A (ExoA) from Pseudomonas aeruginosa is
influenced by iron and is under the control of the regulatory gene regA. To
test whether regA plays a role in the expression of other iron- regulated
proteins a RegA- mutant was constructed by insertional mutagenesis. The
polypeptide pattern of this mutant (PA103R) was compared with the parental
strain (PA103) and a trans-complemented strain PA103R(pREX18) after growth
of the strains in conditions containing low or high concentrations of iron.
An iron-regulated 42 kDa protein (RRP) was identified and purified from the
culture supernatant of PA103 and PA103R(pREX18) which was missing in
PA103R. Database analysis of the N-terminal sequence of this regA-regulated
protein (RRP) revealed no similarity to other proteins. Preliminary
investigations into the function of RRP revealed that it has no proteolytic
or cytotoxic activity. Using two-dimensional electrophoretic analysis of
whole cells, a technique which allowed separation of over 600 polypeptides,
we were unable to identify any other iron-regulated protein whose
expression was regulated by regA.
