1a6x

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STRUCTURE OF THE APO-BIOTIN CARBOXYL CARRIER PROTEIN (APO-BCCP87) OF ESCHERICHIA COLI ACETYL-COA CARBOXYLASE, NMR, 49 STRUCTURES

Overview

The biotin carboxyl carrier protein (BCCP) is a subunit of acetyl-CoA, carboxylase, a biotin-dependent enzyme that catalyzes the first committed, step of fatty acid biosynthesis. In its functional cycle the biotin, carboxyl carrier protein engages in heterologous protein-protein, interactions with three distinct partners, depending on its state of, posttranslational modification. Apo-BCCP interacts specifically with the, biotin holoenzyme synthetase, BirA, which results in the posttranslational, attachment of biotin to an essential lysine residue on BCCP. Holo-BCCP, then interacts with the biotin carboxylase subunit, which leads to the, addition of the carboxylate group of bicarbonate to biotin. Finally, the, carboxybiotinylated form of BCCP interacts with transcarboxylase in the, conversion of acetyl-CoA to malonyl-CoA. The determinants of, protein-protein interaction specificity in this system are unknown. One, hypothesis is that posttranslational modification of BCCP may result in, conformational changes that regulate specific protein-protein, interactions. To test this hypothesis, we have determined the NMR solution, structure of the unbiotinylated form of an 87 residue C-terminal domain, fragment of BCCP (apoBCCP87) from Escherichia coli acetyl-CoA carboxylase, and compared this structure with the high-resolution structure of the, biotinylated form that was recently solved by X-ray crystallographic, techniques. Although the overall folding of the two proteins is highly, similar, small structural differences are apparent for residues of the, biotin-binding loop that may be important for mediating specific, protein-protein interactions.

About this Structure

1A6X is a Single protein structure of sequence from Escherichia coli. Active as Acetyl-CoA carboxylase, with EC number 6.4.1.2 Full crystallographic information is available from OCA.

Reference

Structure of the carboxy-terminal fragment of the apo-biotin carboxyl carrier subunit of Escherichia coli acetyl-CoA carboxylase., Yao X, Wei D, Soden C Jr, Summers MF, Beckett D, Biochemistry. 1997 Dec 9;36(49):15089-100. PMID:9398236

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