Hanks-Type Serine/Threonine Protein Kinases and Phosphatases in Bacteria: Roles in Signaling and Adaptation to Various Environments

Abstract

Reversible phosphorylation is a key mechanism that regulates many cellular processes in prokaryotes and eukaryotes. In prokaryotes, signal transduction includes two-component signaling systems, which involve a membrane sensor histidine kinase and a cognate DNA-binding response regulator. Several recent studies indicate that alternative regulatory pathways controlled by Hanks-type serine/threonine kinases (STKs) and serine/threonine phosphatases (STPs) also play an essential role in regulation of many different processes in bacteria, such as growth and cell division, cell wall biosynthesis, sporulation, biofilm formation, stress response, metabolic and developmental processes, as well as interactions (either pathogenic or symbiotic) with higher host organisms. Since these enzymes are not DNA-binding proteins, they exert the regulatory role via post-translational modifications of their protein targets. In this review, we summarize the current knowledge of STKs and STPs, and discuss how these enzymes mediate gene expression in prokaryotes. Many studies indicate that regulatory systems based on Hanks-type STKs and STPs play an essential role in the regulation of various cellular processes, by reversibly phosphorylating many protein targets, among them several regulatory proteins of other signaling cascades. These data show high complexity of bacterial regulatory network, in which the crosstalk between STK/STP signaling enzymes, components of TCSs, and the translational machinery occurs. In this regulation, the STK/STP systems have been proved to play important roles.

Rules and Exceptions: The Role of Chromosomal ParB in DNA Segregation and Other Cellular Processes

“…An increasing number of important bacterial proteins have been shown to undergo post-translational modifications (PTMs), such as phosphorylation or acetylation [209][210][211]. M. tuberculosis ParB is phosphorylated by Serine/Threonine Protein Kinases (STPKs), including PknB, a key component of the signal transduction pathway that regulates, for example, cell division and the survival of the pathogen in the host [212,213].…”

Role of diversity-generating retroelements for regulatory pathway tuning in cyanobacteria

“…These kinases often control the expression of certain genes [39]. However, Hanks-type STKs have been found in an array of prokaryotic organisms where their genomic abundance is often correlated with genome size, physiological and ecophysiological complexity, and ability to tolerate complex environments [14,38,40]. These STKs are implicated in the regulation of various aspects of bacterial physiology through post-translational modification of proteins, which may themselves be components of phosphorelay and transcriptional regulatory pathways [40][41][42][43].…”

Proteomic Investigation Uncovers Potential Targets and Target Sites of Pneumococcal Serine-Threonine Kinase StkP and Phosphatase PhpP

“…The most abundant signaling systems in bacteria including pneumococci are two-component regulatory systems consisting of a histidine kinase coupled to a cognate response regulator (Jung et al, 2012;Gómez-Mejia et al, 2017). However, previously published studies have demonstrated that eukaryotic-type Ser/Thr protein kinases (ESTKs) as well as Ser/Thr phosphatases (ESTPs) are present in a wide range of bacterial species and operate in parallel or overlapping signaling networks thereby constituting another important signaling mechanism for the regulation of different cellular functions (Shi et al, 2014;Wright and Ulijasz, 2014;Zhang et al, 2017;Janczarek et al, 2018). The pneumococcus presents only one gene encoding an ESTK, stkP, and its respective ESTP, phpP.…”