Characterization of a Novel Two-Component Regulatory System, HptRS, the Regulator for the Hexose Phosphate Transport System in Staphylococcus aureus

Abstract

e Hexose phosphate is an important carbon source within the cytoplasm of host cells. Bacterial pathogens that invade, survive, and multiply within various host epithelial cells exploit hexose phosphates from the host cytoplasm through the hexose phosphate transport (HPT) system to gain energy and synthesize cellular components. In Escherichia coli, the HPT system consists of a two-component regulatory system (UhpAB) and a phosphate sensor protein (UhpC) that tightly regulate expression of a hexose phosphate transporter (UhpT). Although growing evidence suggests that Staphylococcus aureus also can invade, survive, and multiply within various host epithelial cells, the genetic elements involved in the HPT system in S. aureus have not been characterized yet. In this study, we identified and characterized the HPT system in S. aureus that includes the hptRS (a novel two-component regulatory system), the hptA (a putative phosphate sensor), and the uhpT (a hexose phosphate transporter) genes. The hptA, hptRS, and uhpT markerless deletion mutants were generated by an allelic replacement method using a modified pMAD-CM-GFPuv vector system. We demonstrated that both hptA and hptRS are required to positively regulate transcription of uhpT in response to extracellular phosphates, such as glycerol-3-phosphate (G3P), glucose-6-phosphate (G6P), and fosfomycin. Mutational studies revealed that disruption of the hptA, hptRS, or uhpT gene impaired the growth of bacteria when the available carbon source was limited to G6P, impaired survival/multiplication within various types of host cells, and increased resistance to fosfomycin. The results of this study suggest that the HPT system plays an important role in adaptation of S. aureus within the host cells and could be an important target for developing novel antistaphylococcal therapies.

A global Staphylococcus aureus proteome resource applied to the in vivo characterization of host-pathogen interactions

“…The increased levels of GlpK and GlpD might reflect the utilization of glycerol, which is known as one of the preferred carbon sources during intracellular growth of other pathogens such as Listeria monocytogenes 26 . For S. aureus , previous studies reported upregulation of the uhpT gene encoding a hexose phosphate transporter upon internalization 23 , 27 , 28 . Enzymes of the TCA cycle increased in level in S. aureus following internalization as already observed by Surmann et al .…”

Utilization of glycerophosphodiesters by Staphylococcus aureus

“…However, transposon mutants of the two membrane‐anchored glycerophosphodiesterases showed no growth defect in SNM3‐Glu when GroPC was the sole carbon source (data not shown), suggesting that the secreted GlpQ is a major enzyme for the cleavage of GPDs. Transporters for Gro‐3P have been described in S. aureus , GlpT, and UgpT, (Park et al ., ), which may accomplish the uptake of Gro‐3P upon GlpQ‐mediated release from GPDs. GroPC transporters have been described in other bacteria and the potential existence of such a transporter in S. aureus might enable the use of GroPC in SNM3‐Glu media to some degree, even when GlpQ is not present.…”

Bacillithiol: a key protective thiol inStaphylococcusaureus

“…The cell wall synthesis inhibitor fosfomycin is currently used in the treatment of urinary tract and gastrointestinal S. aureus infections. Fosfomycin can enter the cell via the L-α-glycerophosphate transport system and/or the hexose-monophosphate transport system (UhpT) [89]. Mutations in these transporters contribute to fosfomycin resistance and are presumably a major mechanism of fosfomycin resistance [90].…”