1g26 | pdb_00001g26
THE SOLUTION STRUCTURE OF A WELL-FOLDED PEPTIDE BASED ON THE 31-RESIDUE AMINO-TERMINAL SUBDOMAIN OF HUMAN GRANULIN A
Structural highlights
Disease[GRN_HUMAN] Defects in GRN are the cause of ubiquitin-positive frontotemporal dementia (UP-FTD) [MIM:607485]; also known as tau-negative frontotemporal dementia linked to chromosome 17. Frontotemporal dementia (FTD) is the second most common cause of dementia in people under the age of 65 years. It is an autosomal dominant neurodegenerative disease.[1] [2] [3] Defects in GRN are the cause of neuronal ceroid lipofuscinosis type 11 (CLN11) [MIM:614706]. A form of neuronal ceroid lipofuscinosis characterized by rapidly progressive visual loss due to retinal dystrophy, seizures, cerebellar ataxia, and cerebellar atrophy. Cognitive decline may also occur. Neuronal ceroid lipofuscinoses are progressive neurodegenerative, lysosomal storage diseases characterized by intracellular accumulation of autofluorescent liposomal material.[4] Function[GRN_HUMAN] Granulins have possible cytokine-like activity. They may play a role in inflammation, wound repair, and tissue remodeling. Granulin-4 promotes proliferation of the epithelial cell line A431 in culture while granulin-3 acts as an antagonist to granulin-4, inhibiting the growth. Publication Abstract from PubMedFour amino acid substitutions were introduced into a peptide corresponding to the amino-terminal subdomain (30-31 residues) of human granulin A (HGA) in order to assess the contributions of a hydrophobic framework and other interactions to structure stabilization of the stack of two beta-hairpins. The resulting hybrid peptide, HGA 1-31 (D1V, K3H, S9I, Q20P) with four free cysteines, spontaneously formed a uniquely disulfide-bonded isomer with an expected [1-3, 2-4] disulfide pairing pattern. This peptide was characterized in detail by use of NMR and shown to assume a highly stable structure in solution, in contrast to the amino-terminal 1-30 fragment of human granulin A. The prototype peptide, or HGA 1-30 (C17S, C27S), had lower resistance to chemical reduction and proteolysis, broad NH and H(alpha) proton resonances, lower proton resonance dispersion, and no slowly exchanging amide protons. Two other peptides, HGA 1-30 (C17S, Q20P, C27S) and HGA 1-31 (D1V, K3H, S9I, C17S, C27S), with either Pro20 stabilizing a potential reverse turn or with a hydrophobic cluster consisting of Val1, His3, and Ile9, had sharper and slightly better dispersed NH and H(alpha) proton resonances, but still no slowly exchanging amide protons. The solution structure of HGA 1-31 (D1V, K3H, S9I, Q20P) indicates that it adopts a well-folded conformation of a stack of two beta-hairpins, as found for the amino-terminal subdomain of the prototypic carp granulin-1 with representative beta-hairpin stacks. These results highlight the importance of both hydrophobic and turn-stabilizing interactions for the structural integrity of the hairpin stack scaffold. The conformational stability appears to be maintained by a combination of the well-formed second beta-hairpin and two hydrophobic clusters, one located at the interface between the two beta-hairpins and the other on "top" of the first beta-hairpin. The implications of these findings for the design of conformationally stable hairpin stacks are discussed. Design and solution structure of a well-folded stack of two beta-hairpins based on the amino-terminal fragment of human granulin A.,Tolkatchev D, Ng A, Vranken W, Ni F Biochemistry. 2000 Mar 21;39(11):2878-86. PMID:10715107[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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