Conservation of the PTEN catalytic motif in the bacterial undecaprenyl pyrophosphate phosphatase, BacA/UppP

Abstract

Isoprenoid lipid carriers are essential in protein glycosylation and bacterial cell envelope biosynthesis. The enzymes involved in their metabolism (synthases, kinases and phosphatases) are therefore critical to cell viability. In this review, we focus on two broad groups of isoprenoid pyrophosphate phosphatases. One group, containing phosphatidic acid phosphatase motifs, includes the eukaryotic dolichyl pyrophosphate phosphatases and proposed recycling bacterial undecaprenol pyrophosphate phosphatases, PgpB, YbjB and YeiU/LpxT. The second group comprises the bacterial undecaprenol pyrophosphate phosphatase, BacA/UppP, responsible for initial formation of undecaprenyl phosphate, which we predict contains a tyrosine phosphate phosphatase motif resembling that of the tumour suppressor, phosphatase and tensin homologue (PTEN). Based on protein sequence alignments across species and 2D structure predictions, we propose catalytic and lipid recognition motifs unique to BacA/UppP enzymes. The verification of our proposed active-site residues would provide new strategies for the development of substratespecific inhibitors which mimic both the lipid and pyrophosphate moieties, leading to the development of novel antimicrobial agents.

Identification and characterization of SMU.244 encoding a putative undecaprenyl pyrophosphate phosphatase protein required for cell wall biosynthesis and bacitracin resistance in Streptococcus mutans

“…In this study, we were particularly interested in two identified mutants that were highly sensitive to bacitracin and had two independent insertions in the same locus, SMU.244, which encodes a homologue of UppP required for the recycling or de novo synthesis of undecaprenyl phosphate (Up; C 55 -P) (Bickford & Nick, 2013;Chang et al, 2014;El Ghachi et al, 2004). Although the roles of UppP in cell wall biosynthesis and bacitracin resistance are well documented in E. coli, UppP homologues and their physiological features in many Gram-positive bacteria, such as S. mutans, are still lacking.…”

“…For example, bacitracin, a cyclic polypeptide antibiotic that is produced by certain species of Bacillus, can target essential components of the cell envelope and suppresses the biosynthesis of peptidoglycan in many Gram-positive bacteria (Jordan et al, 2008). Bacitracin binds to undecaprenyl pyrophosphate (Upp), the lipid carrier responsible for the translocation of cell envelope precursors from the cytosol to the extracellular side of the cytoplasmic membrane, preventing the dephosphorylation of Upp necessary for the recycling of the lipid carrier (Bickford & Nick, 2013). Interestingly, S. mutans is known to be resistant to bacitracin and this property is often exploited in the isolation of this organism from the highly diverse oral microflora (Liljemark et al, 1976).…”

“…This region is suggested to be essential for the catalytic activity and substrate binding (Chang et al, 2014). Region 2 contained a conserved PGXSRSXXT motif (aa 170-178) that formed a structural P-loop (phosphate-binding loop) commonly found in many phosphate-binding enzymes (Bickford & Nick, 2013;Chang et al, 2014). Sequence alignments also indicated that UppP Sm proteins from five genome-sequence-completed S. mutans strains, UA159, GS-5, LJ2, ATCC25175 and NCTC11060, shared 99 % of identity in their primary sequences (Fig.…”

Proposed Carrier Lipid-binding Site of Undecaprenyl Pyrophosphate Phosphatase from Escherichia coli

“…Tatar et al and Touzé et al (4,9) demonstrated that the active sites of LpxT, YbjG, and PgpB are all oriented toward the periplasmic space and might participate in C 55 -PP recycling based on biochemical evidence and topology analysis. On the contrary, the topological model of UppP revealed a large cytosolic loop that is conserved in bacterial UppP enzymes, suggesting that it may participate in C 55 -PP de novo synthesis in the cytoplasm (4,10). To date, however, it is still unclear on which side of the plasma membrane the dephosphorylation of C 55 -PP molecules occurs.…”

Depletion of Undecaprenyl Pyrophosphate Phosphatases Disrupts Cell Envelope Biogenesis in Bacillus subtilis

“…It may be advantageous, in general, for cells to have UPP-Pase activity localized to both faces of the membrane to facilitate de novo Und-P synthesis (on the inner face) and UPP recycling (on the outer face), and this may account in part for the redundancy commonly observed in UPPPases (6)(7)(8).…”