TY  - JOUR
AU  - Ahmad, Sabahuddin
AU  - Strunk, Christoph Heinrich
AU  - Schott, Stephan
AU  - Jaeger, Karl-Erich
AU  - Kovacic, Filip
AU  - Gohlke, Holger
TI  - Substrate Access Mechanism in a Novel Membrane-Bound Phospholipase A of Pseudomonas aeruginosa Concordant with Specificity and Regioselectivity
JO  - Journal of chemical information and modeling
VL  - 61
IS  - 11
SN  - 0095-2338
CY  - Washington, DC
PB  - American Chemical Society
M1  - FZJ-2021-04293
SP  - 5626–5643
PY  - 2021
AB  - PlaF is a cytoplasmic membrane-bound phospholipase A1 from Pseudomonas aeruginosa that alters the membrane glycerophospholipid (GPL) composition and fosters the virulence of this human pathogen. PlaF activity is regulated by a dimer-to-monomer transition followed by tilting of the monomer in the membrane. However, how substrates reach the active site and how the characteristics of the active site tunnels determine the activity, specificity, and regioselectivity of PlaF for natural GPL substrates have remained elusive. Here, we combined unbiased and biased all-atom molecular dynamics (MD) simulations and configurational free-energy computations to identify access pathways of GPL substrates to the catalytic center of PlaF. Our results map out a distinct tunnel through which substrates access the catalytic center. PlaF variants with bulky tryptophan residues in this tunnel revealed decreased catalysis rates due to tunnel blockage. The MD simulations suggest that GPLs preferably enter the active site with the sn-1 acyl chain first, which agrees with the experimentally demonstrated PLA1 activity of PlaF. We propose that the acyl chain-length specificity of PlaF is determined by the structural features of the access tunnel, which results in favorable free energy of binding of medium-chain GPLs. The suggested egress route conveys fatty acid (FA) products to the dimerization interface and, thus, contributes to understanding the product feedback regulation of PlaF by FA-triggered dimerization. These findings open up opportunities for developing potential PlaF inhibitors, which may act as antibiotics against P. aeruginosa.
LB  - PUB:(DE-HGF)16
C6  - pmid:34748335
UR  - <Go to ISI:>//WOS:000757001900030
DO  - DOI:10.1021/acs.jcim.1c00973
UR  - https://juser.fz-juelich.de/record/902474
ER  -