Highly conserved histidine plays a dual catalytic role in protein splicing: a pKa shift mechanism

Protein splicing is a precise autocatalytic process in which an intein excises itself from a precursor with the concomitant ligation of the flanking sequences. Protein splicing occurs through acid-base catalysis in which the ionization states of active site residues are crucial to the reaction mecha...

Full description

Saved in:
Bibliographic Details
Published in:Journal of the American Chemical Society 2009-08, Vol.131 (32), p.11581-11589
Main Authors: Du, Zhenming, Shemella, Philip T, Liu, Yangzhong, McCallum, Scott A, Pereira, Brian, Nayak, Saroj K, Belfort, Georges, Belfort, Marlene, Wang, Chunyu
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Crystallography, X-Ray
Histidine - chemistry
Histidine - genetics
Hydrogen-Ion Concentration
Inteins
Models, Molecular
Molecular Sequence Data
Mycobacterium tuberculosis - chemistry
Nuclear Magnetic Resonance, Biomolecular
Protein Splicing
Sequence Alignment
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Protein splicing is a precise autocatalytic process in which an intein excises itself from a precursor with the concomitant ligation of the flanking sequences. Protein splicing occurs through acid-base catalysis in which the ionization states of active site residues are crucial to the reaction mechanism. In inteins, several conserved histidines have been shown to play important roles in protein splicing, including the most conserved "B-block" histidine. In this study, we have combined NMR pK(a) determination with quantum mechanics/molecular mechanics (QM/MM) modeling to study engineered inteins from Mycobacterium tuberculosis (Mtu) RecA intein. We demonstrate a dramatic pK(a) shift for the invariant B-block histidine, the most conserved residue among inteins. The B-block histidine has a pK(a) of 7.3 +/- 0.6 in a precursor and a pK(a) of
ISSN:0002-7863
1520-5126
DOI:10.1021/ja904318w