1SMN

IDENTIFICATION OF THE SERRATIA ENDONUCLEASE DIMER: STRUCTURAL BASIS AND IMPLICATIONS FOR CATALYSIS

Summary for 1SMN

• Entry DOI: 10.2210/pdb1smn/pdb
• Descriptor: EXTRACELLULAR ENDONUCLEASE (2 entities in total)
• Functional Keywords: nuclease, dnase, rnase, sugar-nonspecific nuclease, endonuclease
• Biological source: Serratia marcescens
• Cellular location: Secreted: P13717
• Total number of polymer chains: 2
• Total formula weight: 53477.79

Authors

Miller, M.D.,Krause, K.L. (deposition date: 1995-01-25, release date: 1996-01-29, Last modification date: 2024-10-23)

Primary citation

Miller, M.D.,Krause, K.L.
Identification of the Serratia endonuclease dimer: structural basis and implications for catalysis.
Protein Sci., 5:24-33, 1996

PubMed Abstract: The Serratia endonuclease is an extracellularly secreted enzyme capable of cleaving both single- and double-stranded forms of DNA and RNA. It is the first member of a large class of related and usually dimeric endonucleases for which a structure is known. Using X-ray crystallography, the structure of monomer of this enzyme was reported by us previously (Miller MD et al., 1994, Nature Struct Biol 1:461-468). We now confirm the dimeric nature of this enzyme through light-scattering experiments and identify the physiologic dimer interface through crystal packing analysis. This dimerization occurs through an isologous twofold interaction localized to the carboxy-terminal subdomain of the enzyme. The dimer is a prolate ellipsoid with dimensions 30 A x 35 A x 90 A. The dimer interface is flat and contains four salt links, several hydrogen bonds, and nonpolar interactions. Buried water is prominent in this interface and it includes an unusual "cubic" water cluster. The position of the two active sites in the dimer suggests that they can act independently in their cleavage of DNA, but have a geometrical advantage in attacking substrate relative to the monomer.

PubMed: 8771193

Experimental method

X-RAY DIFFRACTION (2.04 Å)