Heme rescues a two-component system Leptospira biflexa mutant

Area of Science:

• Microbiology
• Bacterial Physiology
• Gene Regulation

Background:

• Heme is a primary iron source for many bacteria.
• Limited knowledge exists on heme acquisition in the Leptospira genus.
• Leptospira includes both saprophytic and pathogenic species.

Purpose of the Study:

• Investigate the role of a two-component system in Leptospira biflexa.
• Determine the function of the Hklep/Rrlep system in heme metabolism.
• Explore the regulation of heme biosynthesis in Leptospira.

Main Methods:

• In vitro phosphorylation and site-directed mutagenesis assays.
• Generation of Hklep/Rrlep two-component system mutants in L. biflexa.
• Complementation assays using L. interrogans orthologous genes.
• Real-time quantitative reverse transcription-PCR (RT-qPCR).

Main Results:

• Hklep functions as a histidine kinase, phosphorylating the response regulator Rrlep.
• Mutants lacking the Hklep/Rrlep system required hemin or delta-aminolevulinic acid (ALA) for growth.
• Orthologous genes in L. interrogans are located near heme biosynthesis genes.
• The Hklep/Rrlep system may influence the expression of heme biosynthetic genes.

Conclusions:

• The Hklep/Rrlep regulatory system is vital for in vitro growth of L. biflexa.
• This system appears to play a role in regulating the heme biosynthetic pathway.
• Functional similarity exists between the two-component systems of L. biflexa and L. interrogans.