5‐Enolpyruvylshikimate‐3‐phosphate synthase from Staphylococcus aureus is insensitive to glyphosate

Abstract

The enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) catalyzes the penultimate step of the shikimate pathway, and is the target of the broad-spectrum herbicide glyphosate. Kinetic analysis of the cloned EPSPS from Staphylococcus aureus revealed that this enzyme exerts a high tolerance to glyphosate, while maintaining a high affinity for its substrate phosphoenolpyruvate. Enzymatic activity is markedly influenced by monovalent cations such as potassium or ammonium, which is due to an increase in catalytic turnover. However, insensitivity to glyphosate appears to be independent from the presence of cations. Therefore, we propose that the Staphylococcus aureus EPSPS should be classified as a class II EPSPS. This research illustrates a critical mechanism of glyphosate resistance naturally occurring in certain pathogenic bacteria.

Molecular basis for the herbicide resistance of Roundup Ready crops

“…CP4 EPSP synthase was purified to homogeneity according to the protocol developed for Sta. aureus EPSP synthase (12).…”

“…strain CP4, isolated from a waste-fed column at a glyphosate production facility, yielded a glyphosate-resistant, kinetically efficient EPSP synthase suitable for the production of transgenic, glyphosate-tolerant crops. Other class II EPSP synthases have since been described, typically from Gram-positive bacteria, including pathogenic species such as Streptococcus pneumonia (11) and Staphylococcus aureus (12).…”

“…Another prominent mutation-causing glyphosate insensitivity is Pro-101-Ser in EPSP synthases from Salmonella typhimurium and goosegrass (5, 9, 21) and Pro-101-Leu in EPSP synthase from Sta. aureus (12). In the structure of the CP4 enzyme, the equivalent residue is a Leu residue in position 105, which is part of a helix in the core of the N-terminal domain.…”

“…Notably, other known class II EPSP synthases display greater glyphosate sensitivity and, with the exception of the Sta. aureus enzyme, ions typically affect binding of both PEP and glyphosate (12,16,17).…”

Cloning and characterization of 5-enopyruvylshikimate-3-phosphate synthase from Pantoea sp

“…The Class I enzyme found in all plants and bacteria such as Escherichia coli (Yu et al, 2015) and Salmonella enterica Typhimurium (Garg et al, 2014) is sensitive to glyphosate at low concentrations. The Class II enzyme present in bacterial species such as Pseudomonas sp strain PG2982 (Zhang et al, 2014), Agrobacterium tumefaciens strain CP4 (Heck et al, 2005), Streptococcus pneumoniae (Du et al, 2000), and Staphylococcus aureus (Priestman et al, 2005), however, can tolerate glyphosate even at high concentrations. Class I and II enzymes share less than 30% amino acid similarity (Ye et al, 2001).…”