Neutron crystallography of photoactive yellow protein reveals unusual protonation state of Arg52 in the crystal.

ABSTRACT: Because of its high pK_a, arginine (Arg) is believed to be protonated even in the hydrophobic environment of the protein interior. However, our neutron crystallographic structure of photoactive yellow protein, a light sensor, demonstrated that Arg52 adopts an electrically neutral form. We also showed that the hydrogen bond between the chromophore and Glu46 is a so-called low barrier hydrogen bond (LBHB). Because both the neutral Arg and LBHB are unusual in proteins, these observations remain controversial. To validate our findings, we carried out neutron crystallographic analysis of the E46Q mutant of PYP. The resultant structure revealed that the proportion of the cationic form is higher in E46Q than in WT, although the cationic and neutral forms of Arg52 coexist in E46Q. These

SUBMITTER: Yonezawa K 

PROVIDER: S-EPMC5570954 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature