An IgaA/UmoB Family Protein from Serratia marcescens Regulates Motility, Capsular Polysaccharide Biosynthesis, and Secondary Metabolite Production

作者：Stella Nicholas A; Brothers Kimberly M; Callaghan Jake D; Passerini Angelina M; Sigindere Cihad; Hill Preston J; Liu Xinyu; Wozniak Daniel J; Shanks Robert M Q

来源：Applied and Environmental Microbiology, 2018, 84(6): UNSP e02575-17.

DOI：10.1128/AEM.02575-17

<jats:title>ABSTRACT</jats:title>
<jats:p>
Secondary metabolites are an important source of pharmaceuticals and key modulators of microbe-microbe interactions. The bacterium
<jats:named-content content-type="genus-species">Serratia marcescens</jats:named-content>
is part of the
<jats:named-content content-type="genus-species">Enterobacteriaceae</jats:named-content>
family of eubacteria and produces a number of biologically active secondary metabolites. In this study, we screened for novel regulators of secondary metabolites synthesized by a clinical isolate of
<jats:named-content content-type="genus-species">S. marcescens</jats:named-content>
and found mutations in a gene for an uncharacterized UmoB/IgaA family member here named
<jats:italic>gumB</jats:italic>
. Mutation of
<jats:italic>gumB</jats:italic>
conferred a severe loss of the secondary metabolites prodigiosin and serratamolide. The
<jats:italic>gumB</jats:italic>
mutation conferred pleiotropic phenotypes, including altered biofilm formation, highly increased capsular polysaccharide production, and loss of swimming and swarming motility. These phenotypes corresponded to transcriptional changes in
<jats:italic>fimA</jats:italic>
,
<jats:italic>wecA</jats:italic>
, and
<jats:italic>flhD</jats:italic>
. Unlike other UmoB/IgaA family members,
<jats:italic>gumB</jats:italic>
was found to be not essential for growth in
<jats:named-content content-type="genus-species">S. marcescens</jats:named-content>
, yet
<jats:italic>igaA</jats:italic>
from
<jats:named-content content-type="genus-species">Salmonella enterica</jats:named-content>
,
<jats:italic>yrfF</jats:italic>
from
<jats:named-content content-type="genus-species">Escherichia coli</jats:named-content>
, and an uncharacterized predicted ortholog from
<jats:named-content content-type="genus-species">Klebsiella pneumoniae</jats:named-content>
complemented the
<jats:italic>gumB</jats:italic>
mutant secondary metabolite defects, suggesting highly conserved function. These data support the idea that UmoB/IgaA family proteins are functionally conserved and extend the known regulatory influence of UmoB/IgaA family proteins to the control of competition-associated secondary metabolites and biofilm formation.
</jats:p>
<jats:p>
<jats:bold>IMPORTANCE</jats:bold>
IgaA/UmoB family proteins are found in members of the
<jats:named-content content-type="genus-species">Enterobacteriaceae</jats:named-content>
family of bacteria, which are of environmental and public health importance. IgaA/UmoB family proteins are thought to be inner membrane proteins that report extracellular stresses to intracellular signaling pathways that respond to environmental challenge. This study introduces a new member of the IgaA/UmoB family and demonstrates a high degree of functional similarity between IgaA/UmoB family proteins. Moreover, this study extends the phenomena controlled by IgaA/UmoB family proteins to include the biosynthesis of antimicrobial secondary metabolites.
</jats:p>

• 出版日期2018-3