AUTHOR=Kohler Verena , Keller Walter , Grohmann Elisabeth 

TITLE=Regulation of Gram-Positive Conjugation

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.01134

DOI=10.3389/fmicb.2019.01134

ISSN=1664-302X

ABSTRACT=<p>Type IV Secretion Systems (T4SSs) are membrane-spanning multiprotein complexes dedicated to protein secretion or conjugative DNA transport (conjugation systems) in bacteria. The prototype and best-characterized T4SS is that of the Gram-negative soil bacterium <italic>Agrobacterium tumefaciens</italic>. For Gram-positive bacteria, only conjugative T4SSs have been characterized in some biochemical, structural, and mechanistic details. These conjugation systems are predominantly encoded by self-transmissible plasmids but are also increasingly detected on integrative and conjugative elements (ICEs) and transposons. Here, we report regulatory details of conjugation systems from <italic>Enterococcus</italic> model plasmids pIP501 and pCF10, <italic>Bacillus</italic> plasmid pLS1, <italic>Clostridium</italic> plasmid pCW3, and staphylococcal plasmid pSK41. In addition, regulation of conjugative processes of ICEs (ICE<italic>Bs</italic>1, ICE<italic>St</italic>1, ICE<italic>St</italic>3) by master regulators belonging to diverse repressor families will be discussed. A special focus of this review lies on the comparison of regulatory mechanisms executed by proteins belonging to the RRNPP family. These regulators share a common fold and govern several essential bacterial processes, including conjugative transfer.</p>