The HopF family of Pseudomonas syringae type III secreted effectors

The HopF family of Pseudomonas syringae type III secreted
effectors

Timothy Lo, Noushin Koulena, Derek Seto, David S. Guttman, and Darrell Desveaux

Abstract

Pseudomonas syringae is a bacterial phytopathogen that utilizes
the type III secretion system to inject effector proteins
into plant host cells. Pseudomonas syringae can infect a
wide range of plant hosts, including agronomically important
crops such as tomatoes and beans. The ability of
P. syringae to infect such numerous hosts is caused, in part,
by the diversity of effectors employed by this phytopathogen.
Over 60 different effector families exist in P. syringae; one
such family is HopF, which contains over 100 distinct alleles.
Despite this diversity, research has focused on only two
members of this family: HopF1 from P. syringae pathovar
phaseolicola 1449B and HopF2 from P. syringae pathovar
tomato DC3000. In this study, we review the research on
HopF family members, including their host targets and
molecular mechanisms of immunity suppression, and their
enzymatic function. We also provide a phylogenetic analysis
of this expanding effector family which provides a basis for
a proposed nomenclature to guide future research. The
extensive genetic diversity that exists within the HopF family
presents a great opportunity to study how functional diversification
on an effector family contributes to host
specialization.

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