Unknown

Dataset Information

0

Structure-function studies with the unique hexameric form II ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) from Rhodopseudomonas palustris.


ABSTRACT: The first x-ray crystal structure has been solved for an activated transition-state analog-bound form II ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). This enzyme, from Rhodopseudomonas palustris, assembles as a unique hexamer with three pairs of catalytic large subunit homodimers around a central 3-fold symmetry axis. This oligomer arrangement is unique among all known Rubisco structures, including the form II homolog from Rhodospirillum rubrum. The presence of a transition-state analog in the active site locked the activated enzyme in a "closed" conformation and revealed the positions of critical active site residues during catalysis. Functional roles of two form II-specific residues (Ile(165) and Met(331)) near the active site were examined via site-directed mutagenesis. Substitutions at these residues affect function but not the ability of the enzyme to assemble. Random mutagenesis and suppressor selection in a Rubisco deletion strain of Rhodobacter capsulatus identified a residue in the amino terminus of one subunit (Ala(47)) that compensated for a negative change near the active site of a neighboring subunit. In addition, substitution of the native carboxyl-terminal sequence with the last few dissimilar residues from the related R. rubrum homolog increased the enzyme's kcat for carboxylation. However, replacement of a longer carboxyl-terminal sequence with termini from either a form III or a form I enzyme, which varied both in length and sequence, resulted in complete loss of function. From these studies, it is evident that a number of subtle interactions near the active site and the carboxyl terminus account for functional differences between the different forms of Rubiscos found in nature.

SUBMITTER: Satagopan S 

PROVIDER: S-EPMC4118107 | biostudies-literature | 2014 Aug

REPOSITORIES: biostudies-literature

altmetric image

Publications

Structure-function studies with the unique hexameric form II ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) from Rhodopseudomonas palustris.

Satagopan Sriram S   Chan Sum S   Perry L Jeanne LJ   Tabita F Robert FR  

The Journal of biological chemistry 20140618 31


The first x-ray crystal structure has been solved for an activated transition-state analog-bound form II ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). This enzyme, from Rhodopseudomonas palustris, assembles as a unique hexamer with three pairs of catalytic large subunit homodimers around a central 3-fold symmetry axis. This oligomer arrangement is unique among all known Rubisco structures, including the form II homolog from Rhodospirillum rubrum. The presence of a transition-state a  ...[more]

Similar Datasets

| S-EPMC93548 | biostudies-literature
| S-EPMC8388818 | biostudies-literature
| S-EPMC2676057 | biostudies-literature
| S-EPMC4510133 | biostudies-literature
| S-EPMC3167554 | biostudies-literature
| S-EPMC3711324 | biostudies-literature
| S-EPMC7533879 | biostudies-literature
| S-EPMC5399129 | biostudies-literature
| S-EPMC92794 | biostudies-literature
| S-EPMC2797158 | biostudies-literature