1UAT: The Significance Of The Flexible Loop In The Azurin (Az-Iso2) From The Obligate Methylotroph Methylomonas Sp. Strain J

The obligate methylotroph Methylomonas sp. strain J produces two azurins (Az-iso1 and Az-iso2) as candidates for electron acceptor from methylamine dehydrogenase (MADH) in the electron-transfer process involving the oxidation of methylamine to formaldehyde and ammonia. The X-ray crystallographic study indicated that Az-iso2 gives two types of crystals (form I and form II) with polyethylene glycol (PEG4000) and ammonium sulfate as the precipitants, respectively. Comparison between the two Az-iso2 structures in forms I and II reveals the remarkable structural changes at the top surface of the molecule around the copper atom. Az-iso2 possesses Gly43 instead of Val43 or Ala43, which is unique among all other azurins around the copper ligand His46, inducing the remarkable structural change in the loop region from Gly37 to Gly43. When the structure of Az-iso2 is superimposed on that of amicyanin in the ternary complex composed of MADH, amicyanin, and cytochrome c(551), the loop of Az-iso2 deeply overlaps with the light subunit of MADH. However, the Az-iso2 molecule is probably able to avoid any steric hindrance with the cognate MADH to form the complex for intermolecular electron-transfer reaction, since the loop containing Gly43 is flexible. We discuss why the electron-transfer activity of Az-iso2 is fivefold higher than that of Az-iso1.
PDB ID: 1UATDownload
MMDB ID: 27081
PDB Deposition Date: 2003/3/19
Updated in MMDB: 2012/11
Experimental Method:
x-ray diffraction
Resolution: 1.9  Å
Source Organism:
Similar Structures:
Biological Unit for 1UAT: monomeric; determined by author and by software (PQS)
Molecular Components in 1UAT
Label Count Molecule
Protein (1 molecule)
Azurin Iso-2
Molecule annotation
Chemicals (2 molecules)
* Click molecule labels to explore molecular sequence information.

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