3N4U

app APH(2")-IVa form II

Summary for 3N4U

• Entry DOI: 10.2210/pdb3n4u/pdb
• Related: 3N4V 3n4t
• Descriptor: APH(2'')-Id (2 entities in total)
• Functional Keywords: aminoglycoside, phosphotransferase, resistance, unknown function
• Biological source: Enterococcus casseliflavus (Enterococcus flavescens)
• Total number of polymer chains: 1
• Total formula weight: 35425.41

Authors

Smith, C.A.,Toth, M.,Frase, H.,Vakulenko, S.B. (deposition date: 2010-05-22, release date: 2010-06-30, Last modification date: 2024-02-21)

Primary citation

Toth, M.,Frase, H.,Antunes, N.T.,Smith, C.A.,Vakulenko, S.B.
Crystal structure and kinetic mechanism of aminoglycoside phosphotransferase-2''-IVa.
Protein Sci., 19:1565-1576, 2010

PubMed Abstract: Acquired resistance to aminoglycoside antibiotics primarily results from deactivation by three families of aminoglycoside-modifying enzymes. Here, we report the kinetic mechanism and structure of the aminoglycoside phosphotransferase 2''-IVa (APH(2'')-IVa), an enzyme responsible for resistance to aminoglycoside antibiotics in clinical enterococcal and staphylococcal isolates. The enzyme operates via a Bi-Bi sequential mechanism in which the two substrates (ATP or GTP and an aminoglycoside) bind in a random manner. The APH(2'')-IVa enzyme phosphorylates various 4,6-disubstituted aminoglycoside antibiotics with catalytic efficiencies (k(cat)/K(m)) of 1.5 x 10(3) to 1.2 x 10(6) (M(-1) s(-1)). The enzyme uses both ATP and GTP as the phosphate source, an extremely rare occurrence in the phosphotransferase and protein kinase enzymes. Based on an analysis of the APH(2'')-IVa structure, two overlapping binding templates specifically tuned for hydrogen bonding to either ATP or GTP have been identified and described. A detailed understanding of the structure and mechanism of the GTP-utilizing phosphotransferases is crucial for the development of either novel aminoglycosides or, more importantly, GTP-based enzyme inhibitors which would not be expected to interfere with crucial ATP-dependent enzymes.

PubMed: 20556826
DOI: 10.1002/pro.437

Experimental method

X-RAY DIFFRACTION (2.2 Å)