Biophysical Journal 67: 1117-1125 (1994)
© 1994 the Biophysical Society

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Mancheño, J M Articles by Gavilanes, J G Search for Related Content PubMed PubMed Citation Articles by Mancheño, J M Articles by Gavilanes, J G

Kinetic study of the aggregation and lipid mixing produced by alpha-sarcin on phosphatidylglycerol and phosphatidylserine vesicles: stopped-flow light scattering and fluorescence energy transfer measurements.

Departamento de Bioquímica y Biología Molecular, Facultad de Química, Universidad Complutense, Madrid, Spain.

ABSTRACT

alpha-Sarcin is a fungal cytotoxic protein that inactivates the eukaryotic ribosomes. A kinetic study of the aggregation and lipid mixing promoted by this protein on phosphatidylglycerol (PG) and phosphatidylserine (PS) vesicles has been performed. Egg yolk PG, bovine brain PS, dimyristoyl-PG (DMPG) and dimyristoyl-PS (DMPS) vesicles have been considered. The initial rates of the vesicle aggregation induced by the protein have been measured by stopped-flow 90 degrees light scattering. The formation of a vesicle dimer as the initial step of this process was deduced from the second-order dependence of the initial rates on phospholipid concentration. The highest alpha-sarcin concentration studied did not inhibit the vesicle aggregation, indicating that many protein molecules are involved in the vesicle cross-linking. These are common characteristics of the initial steps of the aggregation produced by alpha-sarcin in the four types of phospholipid vesicles considered. However, the kinetics of the scattering values revealed that more complex changes occurred in the later steps of the aggregation process of egg PG and brain PS vesicles than in those of their synthetic counterparts. alpha-Sarcin produced lipid mixing in vesicles composed of DMPG or DMPS, which was measured by fluorescence resonance energy transfer assays. A delay in the onset of the process, dependent on the protein concentration, was observed. Measurement of the rates of lipid mixing revealed that the process is first order on phospholipid concentration. Egg PG and brain PS vesicles did not show lipid mixing, although they avidly aggregated. However, alpha-sarcin was able to promote lipid mixing in heterogeneous systems composed of egg PG+DMPG or brain PS+DMPS vesicles.(ABSTRACT TRUNCATED AT 250 WORDS)

This article has been cited by other articles:

				L. Garcia-Ortega, M. Masip, J. M. Mancheno, M. Onaderra, M. A. Lizarbe, M. F. Garcia-Mayoral, M. Bruix, A. M. del Pozo, and J. G. Gavilanes Deletion of the NH2-terminal beta -Hairpin of the Ribotoxin alpha -Sarcin Produces a Nontoxic but Active Ribonuclease J. Biol. Chem., May 17, 2002; 277(21): 18632 - 18639. [Abstract] [Full Text] [PDF]

				L. Garcia-ortega, J. Lacadena, J. M. Mancheno, M. Onaderra, R. Kao, J. Davies, N. Olmo, A. M. D. Pozo, and J. G. Gavilanes Involvement of the amino-terminal {beta}-hairpin of the Aspergillus ribotoxins on the interaction with membrances and nonspecific ribonuclease activity Protein Sci., August 1, 2001; 10(8): 1658 - 1668. [Abstract] [Full Text] [PDF]