title: Site specific interaction of the polyphenol EGCG with the SEVI amyloid precursor peptide PAP(248-286).
abstract: Recently, a 39 amino acid peptide fragment from prostatic acid phosphatase has been isolated from seminal fluid that can enhance infectivity of the HIV virus by up to 4-5 orders of magnitude. PAP(248-286) is effective in enhancing HIV infectivity only when it is aggregated into amyloid fibers termed SEVI. The polyphenol EGCG (epigallocatechin-3-gallate) has been shown to disrupt both SEVI formation and HIV promotion by SEVI, but the mechanism by which it accomplishes this task is unknown. Here, we show that EGCG interacts specifically with the side chains of monomeric PAP(248-286) in two regions (K251-R257 and N269-I277) of primarily charged residues, particularly lysine. The specificity of interaction to these two sites is contrary to previous studies on the interaction of EGCG with other amyloidogenic proteins, which showed the nonspecific interaction of EGCG with exposed backbone sites of unfolded amyloidogenic proteins. This interaction is specific to EGCG as the related gallocatechin (GC) molecule, which shows greatly decreased antiamyloid activity, exhibits minimal interaction with monomeric PAP(248-286). The EGCG binding was shown to occur in two steps, with the initial formation of a weakly bound complex followed by a pH dependent formation of a tightly bound complex. Experiments in which the lysine residues of PAP(248-286) have been chemically modified suggest the tightly bound complex is created by Schiff-base formation with lysine residues. The results of this study could aid in the development of small molecule inhibitors of SEVI and other amyloid proteins.
authors.affiliation: Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, USA.
authors.forename: Nataliya
authors.initials: N
authors.lastname: Popovych
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Brender
authors.forename: Ronald
authors.initials: R
authors.lastname: Soong
authors.forename: Subramanian
authors.initials: S
authors.lastname: Vivekanandan
authors.forename: Kevin
authors.initials: K
authors.lastname: Hartman
authors.forename: Venkatesha
authors.initials: V
authors.lastname: Basrur
authors.forename: Peter M
authors.initials: PM
authors.lastname: Macdonald
authors.forename: Ayyalusamy
authors.initials: A
authors.lastname: Ramamoorthy
mesh_terms: D000135:Acid Phosphatase; D000595:Amino Acid Sequence; D002392:Catechin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D015658:HIV Infections / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D011485:Protein Binding; D055503:Protein Multimerization; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry / Q000378:metabolism*; D000685:Serum Amyloid A Protein / Q000737:chemistry / Q000378:metabolism
chemical_list: D000685:Serum Amyloid A Protein; D002392:Catechin; C045651:epigallocatechin gallate; D000135:Acid Phosphatase; C428439:prostatic acid phosphatase; D017027:Protein Tyrosine Phosphatases