Insights into the function of FhaA, a cell-division associated protein in mycobacteria

Abstract

FhaA is a forkhead-associated domain-containing protein, the depletion of which leads to accumulation of peptidoglycan (PG) precursors at the septum and poles in Mycobacterium smegmatis (M. smegmatis), by a mechanism undefined thus far. To elucidate its function, we constructed an fhaA (MSMEG_0035) knockout (ΔfhaA) strain in M. smegmatis and demonstrated that this gene is dispensable for in vitro growth. The mutant showed a short cell length phenotype due to a probable defect in cell elongation/cell wall synthesis, which was reversed by complementation with both M. smegmatis and Mycobacterium tuberculosis (M. tb) fhaA (Rv0020c), confirming their association with the observed phenotype. The identification of penicillin binding protein A (PbpA), a PG biosynthesis enzyme as an interacting partner for mycobacterial FhaA, provided a hint into the functioning of FhaA. A drastic reduction in the levels of ectopically expressed PbpA in the ΔfhaA mutant vs wild-type M. smegmatis suggested that FhaA interacts with and stabilises PbpA. In addition, the fhaA deletion mutant was sensitive to multiple classes of antibiotics pointing to a general permeability defect. Our findings uncover a role for FhaA in PG biosynthesis and suggest its involvement in the maintenance of mycobacterial cell envelope integrity.

Rv0954 Is a Member of the Mycobacterial Cell Division Complex

“…The 19 identified interactors included a serine/threonine protein kinase involved in cell division regulation: PknH (Sharma et al, 2006;Zheng et al, 2007) and two other known divisome proteins: LamA (also known as MmpS3) and PbpA. LamA is a septallocalizing protein that inhibits cell elongation from the new pole, and PbpA is a transpeptidase that localizes to both the septum and poles (Rego et al, 2017;Viswanathan et al, 2017;Arora et al, 2018). We confirmed the interaction between Rv0954 and PknH in Msm by co-immunoprecipitation (Supplementary Figure 2).…”

“…The deletion of pimE in Msm is associated with changes in the cell envelope's structural integrity and increased sensitivity to toxic compounds, such as certain antibiotics and copper (Morita et al, 2006;Eagen et al, 2018). Rv0016c encodes PbpA, a transpeptidase involved in peptidoglycan crosslinking during cell division (Kieser and Rubin, 2014;Viswanathan et al, 2017), and PerM is a divisome component (Goodsmith et al, 2015;Wang et al, 2019). Rv2553 encodes a putative transglycosylase, and its Msm homolog localized to the septum and poles and interacted with FtsQ (Wu et al, 2018).…”

Insight into the PZA resistance whole genome of Mycobacterium tuberculosis isolates from Khyber Pakhtunkhwa, Pakistan

“…In another study the fhaA deletion mutant were created and different classes of antibiotics were screened to check their sensitivity. MTB isolates that were fhaA deletion mutant, have been detected as sensitive to multiple antibiotics showing an overall permeability aw [85]. However, the effect of substitutions has not been evaluated so for, which need to be investigated for future drug development against this target.…”

The enterococcal PASTA kinase: A sentinel for cell envelope stress

“…Phosphorylation at sites within the juxtamembrane linker of PASTA kinases has been described, but the contribution of phosphorylation at these sites to signal transduction has, in most cases, not been elucidated (Boitel et al., 2003; Duran et al., 2005; Madec et al., 2003; Young et al., 2003). When phosphorylated on its juxtamembrane linker, the PASTA kinase of M. tuberculosis was shown to interact with FhaA, a ForkHead Associated (FHA)‐domain containing protein that is involved in PG synthesis (Roumestand et al., 2011; Viswanathan et al., 2017). However, it remains unclear how, or if, that interaction modulates the activity of FhaA or the PASTA kinase itself.…”