1gd4
From Proteopedia
SOLUTION STRUCTURE OF P25S CYSTATIN A
Structural highlights
Disease[CYTA_HUMAN] Defects in CSTA are the cause of ichthyosis exfoliative autosomal recessive ichthyosis bullosa of Siemens-like (AREI) [MIM:607936]. A form of congenital exfoliative ichthyosis, sharing some features with ichthyosis bullosa of Siemens and annular epidermolytic ichthyosis. AREI presents shortly after birth as dry, scaly skin over most of the body with coarse peeling of non-erythematous skin on the palms and soles, which is exacerbated by excessive moisture and minor trauma. Electron microscopy analysis of skin biopsies, reveals mostly normal-appearing upper layers of the epidermis, but prominent intercellular edema of the basal and suprabasal cell layers with aggregates of tonofilaments in the basal keratinocytes.[1] Function[CYTA_HUMAN] This is an intracellular thiol proteinase inhibitor. Has an important role in desmosome-mediated cell-cell adhesion in the lower levels of the epidermis.[2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe effect of substituting Pro25, located in the alpha-helical region of the cystatin A structure, with Ser has been studied. The structures of wild type and P25S cystatin A were determined by multidimensional NMR spectroscopy under comparable conditions. These two structures were virtually identical, and the alpha-helix between Glu15-Lys30 exists with uninterrupted continuity, with a slight bend at residue 25. In order to characterize the possible substitution effects of Pro25 with Ser on the alpha-helix, the chemical shifts of the amide nitrogens and protons, the generalized order parameters obtained by the analyses of the 15N-1H relaxation data, the amide proton exchange rates, and the NOE networks among the alpha-helical and surrounding residues were carefully compared. None of these parameters indicated any significant static or dynamic structural differences between the alpha-helical regions of the wild-type and P25S cystatin A proteins. We therefore conclude that our previous structure of the wild-type cystatin A, in which the alpha-helix exhibited a sharp kink at Pro25, must be revised. The asymmetric distribution of hydrophobic interactions between the side-chain residues of the alpha-helix and the rolled beta-sheet surface, as revealed by NOEs, may be responsible for the slight bend of the alpha-helix in both variants and for the destabilized hydrogen bonding of the alpha-helical residues that follow Pro25/Ser25, as evidenced by increased amide exchange rates. Structural comparison between wild-type and P25S human cystatin A by NMR spectroscopy. Does this mutation affect the alpha-helix conformation?,Shimba N, Kariya E, Tate S, Kaji H, Kainosho M J Struct Funct Genomics. 2000;1(1):26-42. PMID:12836678[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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