Removal of the amino-terminal acidic residues of yeast actin. Studies in vitro and in vivo

R Kimberley Cook; William T Blake; Peter A Rubenstein

doi:10.1016/S0021-9258(19)50441-0

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Removal of the amino-terminal acidic residues of yeast actin. Studies in vitro and in vivo

Journal article

Open access

Peer reviewed

Removal of the amino-terminal acidic residues of yeast actin. Studies in vitro and in vivo

R Kimberley Cook, William T Blake and Peter A Rubenstein

The Journal of biological chemistry, Vol.267(13), pp.9430-9436

05/05/1992

DOI: 10.1016/S0021-9258(19)50441-0

PMID: 1349604

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Abstract

We have examined the role of the acidic residues Asp2 and Glu4 at the NH2 terminus of Saccharomyces cerevisiae actin through site-directed mutagenesis. In DNEQ actin, these residues have been changed to Asn2 and Gln4, whereas in delta DSE actin, the Asp2-Ser-Glu tripeptide has been deleted. Both mutant actins can replace wild type yeast actin. Peptide mapping studies reveal that DNEQ, like wild type actin, retains the initiator Met and is NH2 terminally acetylated, whereas delta DSE has a free NH2 terminus and has lost the initiator Met. Interestingly, microscopic examination of filaments of these two actins reveal the appearance of bundled filaments. The DNEQ bundles are smaller and more ordered, whereas the delta DSE bundles are larger and more loosely organized. Additionally, both mutant actins activate the ATPase activity of rabbit muscle myosin S1 fragment to a lesser extent than wild type. We have also developed a sensitive assay for actin function in vivo that enabled us to detect a slight defect in the ability of these mutant actins to support secretion, an important function in yeast. Thus, although the mutant actins resulted in no gross phenotypic changes, we were able to detect a defect in actin function through this assay. From these studies we can conclude that 1) although NH2-terminal negative charges are not essential to yeast life, the loss of such charges does result in a slight defect in the actins' ability to support secretion, 2) removal of the NH2-terminal negative charges promotes the bundling of actin filaments, and 3) actins lacking NH2-terminal negative charges are unable to activate the myosin S1 ATPase activity as well as wild type actin.

Amino Acid Sequence

Rabbits

Mutagenesis, Site-Directed

Electrophoresis, Polyacrylamide Gel

Actins - metabolism

Actins - ultrastructure

Molecular Sequence Data

Glutamates - metabolism

Microscopy, Electron

Actins - genetics

Glutamic Acid

Saccharomyces cerevisiae - metabolism

Autoradiography

Animals

Muscles - enzymology

Peptide Mapping

Base Sequence

Aspartic Acid - metabolism

Myosins - metabolism

Acetylation

Enzyme Activation

Hydrogen-Ion Concentration

Details

Title: Subtitle: Removal of the amino-terminal acidic residues of yeast actin. Studies in vitro and in vivo
Creators: R Kimberley Cook - Department of Biochemistry, University of Iowa College of Medicine, Iowa City 52242
William T Blake
Peter A Rubenstein
Resource Type: Journal article
Publication Details: The Journal of biological chemistry, Vol.267(13), pp.9430-9436
DOI: 10.1016/S0021-9258(19)50441-0
PMID: 1349604
NLM abbreviation: J Biol Chem
ISSN: 0021-9258
eISSN: 1083-351X
Publisher: United States
Grant note: GM-33689 / NIGMS NIH HHS
Language: English
Date published: 05/05/1992
Academic Unit: Stead Family Department of Pediatrics; Biochemistry and Molecular Biology; Internal Medicine
Record Identifier: 9984024553202771

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