COMPETENCE AND VIRULENCE OF STREPTOCOCCUS-PNEUMONIAE - ADC AND PSAA MUTANTS EXHIBIT A REQUIREMENT FOR ZN AND MN RESULTING FROM INACTIVATIONOF PUTATIVE ABC METAL PERMEASES
A. Dintilhac et al., COMPETENCE AND VIRULENCE OF STREPTOCOCCUS-PNEUMONIAE - ADC AND PSAA MUTANTS EXHIBIT A REQUIREMENT FOR ZN AND MN RESULTING FROM INACTIVATIONOF PUTATIVE ABC METAL PERMEASES, Molecular microbiology, 25(4), 1997, pp. 727-739
The adcCBA putative operon of Streptococcus pneumoniae, an important h
uman pathogen, was identified in a search for transformation-deficient
mutants. It was found to exhibit homology to ATP-binding cassette (AB
C) transport operons encoding streptococcal adhesins such as FimA of S
treptococcus parasanguis and PsaA of S, pneumoniae, The latter was rec
ently shown to be essential for virulence as judged by intranasal or i
ntraperitoneal challenge of mice, We suggested previously that AdcA, t
ogether with a set of 14 proteins, including PsaA and homologous adhes
ins, defines a new family of external solute-binding proteins specific
for metals, In this work, Northern analysis revealed the existence of
two adcB-adcA specific transcripts originating within adcC or further
upstream, consistent with the hypothesis that ade is an operon, Inves
tigation of growth of ade and psaA mutants in synthetic medium reveale
d that the addition of Zn improved the growth rate of the former, wher
eas the latter exhibited an absolute requirement for added Mn, A psaA-
adc double mutant turned out to be essentially non-viable unless both
metals were added in the appropriate ratio. Taken together, these resu
lts suggest a previously undocumented requirement of S. pneumoniae for
Zn and Mn, The addition of Zn also restored near-normal spontaneous t
ransformation of ade mutant cells in standard transformation medium. Z
n was found to be specifically required soon after contact of cells wi
th the competence-stimulating peptide, revealing an unsuspected need f
or Zn in transformation of S, pneumoniae, The removal of Mn from stand
ard transformation medium also resulted in transformation deficiency o
f psaA mutant cells. Taken together, these results lead us to propose
that Adc is an ABC-type Zn permease, the first such protein complex id
entified in any organism, and that Psa ia an ABC-type Mn permease comp
lex.