TY - JOUR
T1 - A structurally dynamic N-terminal region drives function of the staphylococcal peroxidase inhibitor (SPIN)
AU - De Jong, Nienke W.M.
AU - Ploscariu, Nicoleta T.
AU - Ramyar, Kasra X.
AU - Garcia, Brandon L.
AU - Herrera, Alvaro I.
AU - Prakash, Om
AU - Katz, Benjamin B.
AU - Leidal, Kevin G.
AU - Nauseef, William M.
AU - Van Kessel, Kok P.M.
AU - Van Strijp, Jos A.G.
AU - Geisbrecht, Brian V.
N1 - Funding Information:
This work was supported by ZonMw Grant 205200004 from the Netherlands Organization for Health Research and Development (to J. A. G. v. S.), National Institutes of Health Grants AI111203 and GM121511 (to B. V. G.) and AI116546 (to W. M. N.), and a Merit Review Award (to the Nauseef laboratory). The authors declare that they have no conflicts of interest with the contents of this article. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Funding Information:
Acknowledgments—X-ray diffraction data were collected at South-east Regional Collaborative Access Team (SER-CAT) 22-BM beam-line at the Advanced Photon Source, Argonne National Laboratory. Use of the Advanced Photon Source was supported by the United States Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. W-31-109-Eng-38. Use of the facilities at the Iowa City, IA, Department of Veterans Affairs Medical Center, was supported by a Merit Review award.
Publisher Copyright:
© 2018 American Society for Biochemistry and Molecular Biology Inc. All rights reserved.
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2018/1/1
Y1 - 2018/1/1
N2 - The heme-containing enzyme myeloperoxidase (MPO) is critical for optimal antimicrobial activity of human neutrophils. We recently discovered that the bacterium Staphylococcus aureus expresses a novel immune evasion protein, called SPIN, that binds tightly to MPO, inhibits MPO activity, and contributes to bacterial survival following phagocytosis. A co-crystal structure of SPIN bound to MPO suggested that SPIN blocks substrate access to the catalytic heme by inserting an N-terminal β-hairpin into the MPO active-site channel. Here, we describe a series of experiments that more completely define the structure/function relationships of SPIN. Whereas the SPIN N terminus adopts a β-hairpin confirmation upon binding to MPO, the solution NMR studies presented here are consistent with this region of SPIN being dynamically structured in the unbound state. Curiously, whereas the N-terminal β-hairpin of SPIN accounts for ∼55% of the buried surface area in the SPIN-MPO complex, its deletion did not significantly change the affinity of SPIN for MPO but did eliminate the ability of SPIN to inhibit MPO. The flexible nature of the SPIN N terminus rendered it susceptible to proteolytic degradation by a series of chymotrypsin-like proteases found within neutrophil granules, thereby abrogating SPIN activity. Degradation of SPIN was prevented by the S. aureus immune evasion protein Eap, which acts as a selective inhibitor of neutrophil serine proteases. Together, these studies provide insight into MPO inhibition by SPIN and suggest possible functional synergy between two distinct classes of S. aureus immune evasion proteins.
AB - The heme-containing enzyme myeloperoxidase (MPO) is critical for optimal antimicrobial activity of human neutrophils. We recently discovered that the bacterium Staphylococcus aureus expresses a novel immune evasion protein, called SPIN, that binds tightly to MPO, inhibits MPO activity, and contributes to bacterial survival following phagocytosis. A co-crystal structure of SPIN bound to MPO suggested that SPIN blocks substrate access to the catalytic heme by inserting an N-terminal β-hairpin into the MPO active-site channel. Here, we describe a series of experiments that more completely define the structure/function relationships of SPIN. Whereas the SPIN N terminus adopts a β-hairpin confirmation upon binding to MPO, the solution NMR studies presented here are consistent with this region of SPIN being dynamically structured in the unbound state. Curiously, whereas the N-terminal β-hairpin of SPIN accounts for ∼55% of the buried surface area in the SPIN-MPO complex, its deletion did not significantly change the affinity of SPIN for MPO but did eliminate the ability of SPIN to inhibit MPO. The flexible nature of the SPIN N terminus rendered it susceptible to proteolytic degradation by a series of chymotrypsin-like proteases found within neutrophil granules, thereby abrogating SPIN activity. Degradation of SPIN was prevented by the S. aureus immune evasion protein Eap, which acts as a selective inhibitor of neutrophil serine proteases. Together, these studies provide insight into MPO inhibition by SPIN and suggest possible functional synergy between two distinct classes of S. aureus immune evasion proteins.
KW - neutrophil
KW - myeloperoxidase
KW - Protein-protein interaction
KW - innate immunity
KW - Staphylococcus aureus (S. aureus)
KW - immune evastion
KW - SPIN
UR - http://www.scopus.com/inward/record.url?scp=85042165619&partnerID=8YFLogxK
U2 - 10.1074/jbc.RA117.000134
DO - 10.1074/jbc.RA117.000134
M3 - Article
AN - SCOPUS:85042165619
SN - 0021-9258
VL - 293
SP - 2260
EP - 2271
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 7
ER -