Structural basis for the substrate recognition of aminoglycoside 7 ′ ′ -phosphotransferase-Ia from Streptomyces hygroscopicus

Hygromycin B (HygB) is one of the aminoglycoside antibiotics, and it is widely used as a reagent in molecular-biology experiments. Two kinases are known to inactivate HygB through phosphorylation: aminoglycoside 7 ′ ′ -phosphotransferase-Ia [APH(7 ′ ′ )-Ia] from Streptomyces hygroscopicus and aminoglycoside 4-phosphotransferase-Ia [APH(4)-Ia] from Escherichia coli. They phosphorylate the hydroxyl groups at positions 7 ′ ′ and 4 of the HygB molecule, respectively. Previously, the crystal structure of APH(4)-Ia was reported as a ternary complex with HygB and 5 ′ -adenylyl- β , γ -imidodiphosphate (AMP-PNP). To investigate the differences in the substrate-recognition mechanism between APH(7 ′ ′ )-Ia and APH(4)-Ia, the crystal structure of APH(7 ′ ′ )-Ia complexed with HygB is reported. The overall structure of APH(7 ′ ′ )-Ia is similar to those of other aminoglycoside phosphotransferases, including APH(4)-Ia, and consists of an N-terminal lobe (N-lobe) and a C-terminal lobe (C-lobe). The latter also comprises a core and a helical domain. Accordingly, the APH(7 ′ ′ )-Ia and APH(4)-Ia structures fit globally when the structures are superposed at three catalytically important conserved residues, His, Asp and Asn, in the Brenner motif, which is conserved in aminoglycoside phosphotransferases as well as in eukaryotic protein kinases. On the other hand, the phosphorylated hydroxyl groups of HygB in both structures come close to the Asp residue, and the ...
Source: Acta Crystallographica Section F - Category: Biochemistry Authors: Tags: aminoglycoside antibiotics enzyme-mediated resistance kinases SAD phasing selenomethionine hygromycin B Streptomyces hygroscopicus research communications Source Type: research