Mechanism of Calcite Crystal Growth Inhibition by the N-terminal Undecapeptide of Lithostathine

Abstract

Pancreatic juice is supersaturated with calcium carbonate. Calcite crystals therefore may occur, obstruct pancreatic ducts, and finally cause a lithiasis. Human lithostathine, a protein synthesized by the pancreas, inhibits the growth of calcite crystals by inducing a habit modification: the rhombohedral {10 1 4} usual habit is transformed into a needle-like habit through the {11 2 0} crystal form. A similar observation was made with the N-terminal undecapeptide (pE 1 R 11 ) of lithostathine. We therefore aimed at discovering how peptides inhibit calcium salt crystal growth. We solved the complete x-ray structure of lithostathine, including the flexible N-terminal domain, at 1.3 Å. Docking studies of pE 1 R 11 with the (10 1 4) and (11 2 0) faces through molecular dynamics simulation resulted in three successive steps. First, the undecapeptide progressively unfolded as it approached the calcite surface. Second, mobile lateral chains of amino acids made hydrogen bonds with the calcite surface. Last, electrostatic bonds between calcium ions and peptide bonds stabilized and anchored pE 1 R 11 on the crystal surface. pE 1 R 11 -calcite interaction was stronger with the (11 2 0) face than with the (10 1 4) face, confirming earlier experimental observations. Energy contributions showed that the peptide backbone governed the binding more than did the lateral chains. The ability of peptides to inhibit crystal growth is therefore essentially based on backbone flexibility.

Intrinsically Disordered Proteins in Biomineralization

“…Mammals DMP1 4.0 CD, DLS, FTIR, SAXS (Gericke et al, 2010;He et al, 2003aHe et al, , 2003b DPP 2.8 CD, NMR, SAXS (Cross et al, 2005;Evans et al, 1994;Fujisawa & Kuboki, 1998;George & Hao, 2005;He et al, 2005b;Lee et al, 1977) BSP 4.1 CD, NMR, SAXS (Fisher et al, 2001;Tye et al, 2003Tye et al, , 2005Wuttke et al, 2001) OPN 4.4 CD, NMR, FTIR (Fisher et al, 2001;Gorski et al, 1995) amelogenin 6.6 CD, NMR (Buchko et al, 2010;Delak et al, 2009b;Ndao et al, 2011;Shaw et al, 2008) statherin 8.0 CD, NMR (Long et al, 2001;Naganagowda et al, 1998;Raj et al, 1992) lithostathine 5.7 CD (Gerbaud et al, 2000) Haliotis rufescens AP7 5.2 CD, NMR (Kim et al, 2004(Kim et al, , 2006aMichenfelder et al, 2003;Wustman et al, 2004) Atrina rigita Asprich 2.7-3.5 CD, NMR (Collino et al, 2006;Delak et al, 2009aDelak et al, , 2008Kim et al, 2008;Ndao et al, 2010) Procambrus clarkii CAP-1 3.9 CD (Inoue et al, 2007) Strongylocentrotus purpuratus SM50 10.8 CD, NMR (Xu & Evans, 1999;Zhang et al, 2000) PM27 8.1 CD, NMR Danio rerio Stm 4.1 CD, gel filtration (Kaplon et al, 2008(Kaplon et al, , 2009 Table 1. IDPs involved in biomineralization of calcium carbonate and phosphate for which a disordered structure has been confirmed...…”

“…However, the 13 residues of the N-terminus, including the glycosylation site, are flexibile in the crystal (Bertrand et al, 1996). Far UV CD spectra of the N-terminal region are typical for random-coil structures (Table 1) (Gerbaud et al, 2000). Interestingly, the short N-terminal peptide of lithostathine is essential for the inhibition of nucleation and crystal growth.…”

High-speed atomic force microscopy coming of age

“…Lithosthatine (also named Reg-1) of 144 amino acids is produced 23 by pancreas acinar cells and secreted into pancreatic juice. It tightly binds calcium carbonate and may act as an inhibitor of calcium carbonate precipitation to prevent clogging of pancreatic duct [177,178]. In chronic calcifying pancreatitis, the protein forms deposits in pancreatic duct [179].…”

Solid state NMR studies of molecular recognition at protein–mineral interfaces

“…These models are derived from the full set of 1,000 models. Alignment of the models in the figure was based on root-mean-square deviation calculation of segments (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) and (33)(34)(35)(36)(37)(38) between the 8 models. Table 1 31 P-31 P nearest neighbor distances lying within a sphere of radius 6 Å for the 004 crystal plane in in monoclinic HAP.…”

“…The conventional methods of high resolution structural biology, i.e. X-ray crystallography and solution nuclear magnetic resonance (NMR) spectroscopy, have provided information on a few biomineralization proteins in the pure crystalline and solution states [6][7][8][9], but both techniques are severely limited in their abilities to elucidate the structures of proteins on biomineral surfaces. Although traditional surface science methods like photo-electron spectroscopy and NEXAFS have provided important information on protein adsorbed onto planar surfaces, and in particular may be used to characterize the degree of long range ordering in systems of adsorbed proteins on polymer surfaces as well as average structural properties, these techniques have yet to provide detailed atomic-level structural information for surfaceadsorbed proteins.…”