Antibacterial peptides and mitochonrial presequences affect mitochonrial coupling, respiration and protein import

Abstract

Cecropins A and P1, antibacterial peptides from insects and from pig and some related peptides released respiratory control, inhibited protein import and at higher concentrations also inhibited respiration. However, PR-39, an antibacterial peptide from pig intestine, was found to be almost inert towards mitochondria. The concentrations at which the three mitochondrial functions were effected varied for different peptides. Melittin, magainin and Cecropin-A-(1,13) -Melittin(l,l3)-NH2, a hybrid between cecropin A and melittin, were most potent, while the two cecropins acted at higher concentrations. The biosynthesis of cecropin A is known and the intermediates are synthesized. We have used four peptides from this pathway to investigate their effects on coupling, respiration and protein import into mitochondria. Mature cecropin A followed by the preproprotein were most aggressive whereas the intermediates were less active or inert. The efficiency of different derivatives of cecropin A as uncouplers correlates well with their capacity to release membrane potential measured as fluorescence quenching of Rhodamine 123. Inhibition of respiration was found to be dependent on membrane potential and was most pronounced with mature cecropin A, less so with its three precursors. We also found that three peptides derived from mitochondrial presequences showed antibacterial activity. It is concluded that, there are similarities in the functions of antibacterial peptides and mitochondrial presequences, uncoupling activity in mitochondria cannot be correlated with the antibacterial activity (contrary to a previous suggestion), the processing of preprocecropin A may have evolved in such a way that there is a minimum of membrane damage from the intermediates in the pathway, and peptides produced for delivery outside of an animal have evolved to be more aggressive against mitochondria than peptides for delivery inside of the animal.During the last 13 years several classes of broadspectrum antibacterial peptides have been discovered in the animal kingdom, among them cecropins, defensins and magainins (reviewed by Boman, 1991 ;Zasloff, 1992). These three groups of peptides are well characterized, they have been cloned, their three-dimensional structures are known and for cecropins and defensins the gene structures have been determined. All three groups of peptides also form channels in artificial membranes but it is not yet known if channel formation is responsible for the lethal activity on bacteria. There are clear structural similarities between certain antiCorrespondence to E. Glaser,

The Cellular Target of Histatin 5 on Candida albicans Is the Energized Mitochondrion

“…These peptides also display antimicrobial activity (31). Likewise, Westerhoff et al (29,32) showed that magainins dissipated the membrane potential of isolated rat liver mitochondria and postulated that this would be the mechanism of antibacterial activity, because of the similar organization of membrane-linked energy coupling in bacteria and mitochondria.…”

Porcine antimicrobial peptides: New prospects for ancient molecules of host defense

“…However, the primary sequence is the determining factor, because the reverse sequence was inactive against the bacteria tested. Cecropin P1 is also capable of uncoupling oxidative phosphorylation in the mitochondria, but this activity is not correlated with its antibacterial activity [59].…”

Organellar oligopeptidase (OOP) provides a complementary pathway for targeting peptide degradation in mitochondria and chloroplasts

“…28). Additionally, it has long been known that presequence peptides destabilize mitochondrial membranes, potentially leading to uncoupling of respiration or to dissipation of the membrane potential (29)(30)(31)(32). Accumulation of presequences also was shown to impair mitochondrial precursor processing by direct inhibition of MPP activity (33).…”