Delineating the molecular basis of the inactivity of tissue inhibitor of metalloproteinase-2 against tumor necrosis factor-alpha-converting enzyme.
Tumor necrosis factor-alpha (TNF-alpha)-converting enzyme (TACE, ADAM-17) is a zinc-dependent ADAM (a disintegrin and metalloproteinase) metalloproteinase (MP) of the metzincin superfamily. The enzyme regulates the shedding of a variety of cell surface-anchored molecules such as cytokines, growth factors, and receptors. The activities of the MPs are modulated by the endogenous inhibitors, the tissue inhibitor of metalloproteinases (TIMPs). Among the four mammalian TIMPs (TIMP-1 to -4), TACE is selectively inhibited by TIMP-3. The rationale for such selectivity is not fully understood. Here, we examine the molecular basis of TIMP-TACE selectivity using TIMP-2 as the scaffold. By systematically replacing the surface epitopes of TIMP-2 with those of TIMP-3 and a TIMP-1 variant V4S/TIMP-3 AB-loop/V69L/T98L, we created a novel TIMP-2 mutant that exhibits inhibitory potency almost equal to that of the TIMP-3. The affinity of the mutant with TACE is 1.49 nm, a marked improvement in comparison to that of the wild-type protein (Ki 893 nM). The inhibitory pattern of the mutant is typical of that of a slow, tight binding inhibitor. We identify phenylalanine 34, a residue unique to the TIMP-3 AB-loop, as a vital element in TACE association. Mutagenesis carried out on leucine 100 also upholds our previous findings that a leucine on the EF-loop is critical for TACE recognition. Replacement of the residue by other amino acids resulted in a dramatic decrease in binding affinity, although isoleucine (L100I) and methionine (L100M) are still capable of producing the slow, tight binding effect. Our findings here represent a significant advance toward designing tailor-made TIMPs for specific MP targeting.
Department of Oncology, Cambridge University, Cambridge Institute for Medical Research, Wellcome Trust/Medical Research Council Building, Cambridge CB2 2XY, United Kingdom.
Meng-Huee
MH
Lee
Magdalini
M
Rapti
Gillian
G
Murphy
D051722:ADAM Proteins; D000072198:ADAM17 Protein; D000595:Amino Acid Sequence; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry; D018076:DNA, Complementary / Q000378:metabolism; D000939:Epitopes / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism; D006801:Humans; D007532:Isoleucine / Q000737:chemistry; D007700:Kinetics; D007930:Leucine / Q000737:chemistry; D008666:Metalloendopeptidases / Q000737:chemistry; D008715:Methionine / Q000737:chemistry; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010649:Phenylalanine / Q000737:chemistry; D011485:Protein Binding; D011489:Protein Denaturation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013912:Threonine / Q000737:chemistry; D013997:Time Factors; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000737:chemistry* / Q000378:metabolism
D018076:DNA, Complementary; D000939:Epitopes; D007532:Isoleucine; D019716:Tissue Inhibitor of Metalloproteinase-2; D013912:Threonine; D010649:Phenylalanine; D004247:DNA; D008715:Methionine; D051722:ADAM Proteins; D008666:Metalloendopeptidases; D000072198:ADAM17 Protein; C000606462:ADAM17 protein, human; D007930:Leucine