Dataset Information

Conserved properties of individual Ca2+-binding sites in calmodulin.

ABSTRACT: Calmodulin (CaM) is a Ca(2+)-sensing protein that is highly conserved and ubiquitous in eukaryotes. In humans it is a locus of life-threatening cardiomyopathies. The primary function of CaM is to transduce Ca(2+) concentration into cellular signals by binding to a wide range of target proteins in a Ca(2+)-dependent manner. We do not fully understand how CaM performs its role as a high-fidelity signal transducer for more than 300 target proteins, but diversity among its four Ca(2+)-binding sites, called EF-hands, may contribute to CaM's functional versatility. We therefore looked at the conservation of CaM sequences over deep evolutionary time, focusing primarily on the four EF-hand motifs. Expanding on previous work, we found that CaM evolves slowly but that its evolutionary rate is substantially faster in fungi. We also found that the four EF-hands have distinguishing biophysical and structural properties that span eukaryotes. These results suggest that all eukaryotes require CaM to decode Ca(2+) signals using four specialized EF-hands, each with specific, conserved traits. In addition, we provide an extensive map of sites associated with target proteins and with human disease and correlate these with evolutionary sequence diversity. Our comprehensive evolutionary analysis provides a basis for understanding the sequence space associated with CaM function and should help guide future work on the relationship between structure, function, and disease.

SUBMITTER: Halling DB

PROVIDER: S-EPMC4780646 | biostudies-literature | 2016 Mar

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Conserved properties of individual Ca2+-binding sites in calmodulin.

Halling D Brent DB Liebeskind Benjamin J BJ Hall Amelia W AW Aldrich Richard W RW

Proceedings of the National Academy of Sciences of the United States of America 20160216 9

Calmodulin (CaM) is a Ca(2+)-sensing protein that is highly conserved and ubiquitous in eukaryotes. In humans it is a locus of life-threatening cardiomyopathies. The primary function of CaM is to transduce Ca(2+) concentration into cellular signals by binding to a wide range of target proteins in a Ca(2+)-dependent manner. We do not fully understand how CaM performs its role as a high-fidelity signal transducer for more than 300 target proteins, but diversity among its four Ca(2+)-binding sites, ...[more]

PMID: 26884197

Similar Datasets

Project description:Factor H exists as a 155,000 dalton, extended protein composed of twenty small domains which is flexible enough that it folds back on itself. Factor H regulates complement activation through its interactions with C3b and polyanions. Three binding sites for C3b and multiple polyanion binding sites have been identified on Factor H. In intact Factor H these sites appear to act synergistically making their individual contributions difficult to distinguish. Recombinantly expressed fragments of human Factor H were examined using surface plasmon resonance (SPR) for interactions with C3, C3b, iC3b, C3c, and C3d. Eleven recombinant proteins of lengths from one to twenty domains were used to show that the three C3b-binding sites exhibit 100-fold different affinities for C3b. The N-terminal site [complement control protein (CCP) domains 1-6] bound C3b with a K d of 0.08 μM and this interaction was not influenced by the presence or absence of domains 7 and 8. Full length Factor H similarly exhibited a K d for C3b of 0.1 μM. Unexpectedly, the N-terminal site (CCP 1-6) bound native C3 with a K d of 0.4 μM. The C-terminal domains (CCP 19-20) exhibited a K d of 1.7 μM for C3b. We localized a weak third C3b binding site in the CCP 13-15 region with a K d estimated to be ~15 μM. The C-terminal site (CCP 19-20) bound C3b, iC3b, and C3d equally well with a K d of 1 to 2 μM. In order to identify and compare regions of Factor H that interact with polyanions a family of 18 overlapping three domain recombinant proteins spanning the entire length of Factor H were expressed and purified. Immobilized heparin was used as a model polyanion and SPR confirmed the presence of heparin binding sites in CCP 6-8 (K d 1.2 μM) and in CCP 19-20 (4.9 μM) and suggested the existence of a weak third polyanion binding site in the center of Factor H (CCP 11-13). Our results unveil the relative contributions of different regions of Factor H to its regulation of complement, and may contribute to the understanding of how defects in certain Factor H domains lead to disease.

Dataset Information

Conserved properties of individual Ca2+-binding sites in calmodulin.

Publications

Conserved properties of individual Ca2+-binding sites in calmodulin.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets