4OQO

Crystal structure of the tryptic generated iron-free C-lobe of bovine Lactoferrin at 2.42 Angstrom resolution

Summary for 4OQO

• Entry DOI: 10.2210/pdb4oqo/pdb
• Related: 3TAJ
• Descriptor: Lactotransferrin, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, 2-acetamido-2-deoxy-beta-D-glucopyranose, ... (4 entities in total)
• Functional Keywords: c-lobe, hydrolase
• Biological source: Bos taurus (bovine,cow,domestic cattle,domestic cow)
• Total number of polymer chains: 2
• Total formula weight: 77141.95

Authors

Singh, A.,Rastogi, N.,Pandey, S.,Bhushan, A.,Sinha, M.,Kaur, P.,Sharma, S.,Singh, T.P. (deposition date: 2014-02-10, release date: 2014-03-12, Last modification date: 2024-10-30)

Primary citation

Rastogi, N.,Singh, A.,Pandey, S.N.,Sinha, M.,Bhushan, A.,Kaur, P.,Sharma, S.,Singh, T.P.
Structure of the iron-free true C-terminal half of bovine lactoferrin produced by tryptic digestion and its functional significance in the gut.
Febs J., 281:2871-2882, 2014

PubMed Abstract: Bovine lactoferrin, a 76-kDa glycoprotein (Ala1-Arg689) consists of two similar N- and C-terminal molecular halves with the ability to bind two Fe(3+) ions. The N-terminal half, designated as the N-lobe (Ala1-Arg341) and the C-terminal half designated as the C-lobe (Tyr342-Arg689) have similar iron-binding properties, but the resistant C-lobe prolongs the physiological role of bovine lactoferrin in the digestive tract. Here, we report the crystal structure of true C-lobe, which was produced by limited proteolysis of bovine lactoferrin using trypsin. In the first proteolysis step, two fragments of 21 kDa (Glu86-Lys282) and 45 kDa (Ser283-Arg689) were generated because two lysine residues, Lys85 and Lys282, in the structure of iron-saturated bovine lactoferrin were fully exposed. The 45-kDa fragment was further digested at the newly exposed side chain of Arg341, generating a 38-kDa perfect C-lobe (Tyr342-Arg689). By contrast, the apo-lactoferrin was cut by trypsin only at Arg341, which was exposed in the structure of apo-lactoferrin, whereas the other two sites with Lys85 and Lys282 are inaccessible. The purified iron-saturated C-lobe was crystallized at pH 4.0. The structure was determined by the molecular replacement method using coordinates of the C-terminal half (Arg342-Arg689) of intact camel apo-lactoferrin. The structure determination revealed that the iron atom was absent and the iron-binding cleft was found in a wide-open conformation, whereas in the previously determined structure of iron-saturated C-lobe of bovine lactoferrin, the iron atom was present and the iron-binding site was in the closed confirmation.

PubMed: 24798798
DOI: 10.1111/febs.12827

Experimental method

X-RAY DIFFRACTION (2.42 Å)