Modification of Autolysis by Synthetic Peptides Derived from the Presumptive Binding Domain of Staphylococcus aureus Autolysin

Abstract

The autolytic cell wall hydrolase of Staphylococcus aureus, Atl, contains three highly cationic repeats in the central region of the amino acid sequence, and the repeats are presumed to have the role of binding the enzyme to some components on the cell surface. To explain the possible function of the repeats, we synthesized a number of 10-to 30-mer oligopeptides based on the Atl amino acid sequence (Thr432-Lys610) containing repeat 1, and examined their effects on the autolysis of S. aureus cells. When the peptides were added to a cell suspension of S. aureus under low ionic strength conditions, five peptides, A10, All, A14, A16 and B9, showed immediate increases in optical density (OD) of the cell suspension accompanied by decreases in viable cell counts. After the immediate increases, the ODs for A10 and A14 changed little in the first 2 hr. In contrast, the ODs for All and Al6 decreased rapidly. When peptide A10 was added to suspensions of heat-killed whole cells, crude cell walls and a crude peptidoglycan preparation, their ODs were increased approximately 2-fold. In contrast, the OD was not increased when the peptide was added to a suspension of pure peptidoglycan from which anionic polymers had been removed. Light microscopic and transmission electron microscopic study showed that A10 and Al4 inhibited autolysis and that All and A16 induced autolysis earlier than the control. These results suggest strongly that the peptides adsorb to and precipitate on the anionic cell surface polymers such as teichoic acid and lipoteichoic acid via ionic interaction. The effects of peptides on the autolysis may be the results of the modification of S. aureus autolysin activities. These peptides, especially the 10-mer peptide B9 (PGTKLYTVPW) that represents the C-terminal half of A10 and N-terminal half of All, may be important segments for Atl to bind to the cell surface.

The Auxiliary Role of the Amidase Domain in Cell Wall Binding and Exolytic Activity of Staphylococcal Phage Endolysins

“…LSA12AMICBD and LSA12AMI did not inhibit the growth of cells, but rather caused a slight increase in the OD values ( Figure 3 A,B). It has been reported that the negatively charged teichoic acid and lipoteichoic acid on the surface of S. aureus cells can interact with positively charged proteins to increase the OD value [ 28 ]. The calculated pI values of the truncated proteins of LysSA12 with no lytic activity are 5.3 for LSA12CHAP, 8.73 for LSA12CHAPAMI, 9.18 for LSA12AMICBD, and 9.38 for LSA12AMI, suggesting that the positively charged LSA12AMICBD and LSA12AMI with high pI values caused an increase in OD value as reported by Takano et al [ 28 ].…”

“…It has been reported that the negatively charged teichoic acid and lipoteichoic acid on the surface of S. aureus cells can interact with positively charged proteins to increase the OD value [ 28 ]. The calculated pI values of the truncated proteins of LysSA12 with no lytic activity are 5.3 for LSA12CHAP, 8.73 for LSA12CHAPAMI, 9.18 for LSA12AMICBD, and 9.38 for LSA12AMI, suggesting that the positively charged LSA12AMICBD and LSA12AMI with high pI values caused an increase in OD value as reported by Takano et al [ 28 ]. LSA12CHAP, LSA12AMI, and LSA12CHAPAMI barely lysed the intact S. aureus cells, whereas LSA12CHAPCBD and the full length LysSA12 resulted in clear lysis, suggesting that the both CHAP and a C-terminal CBD are necessary to exert the lytic activity of LysSA12.…”

Staphylococcus caprae Strains Carry Determinants Known To Be Involved in Pathogenicity: a Gene Encoding an Autolysin-Binding Fibronectin and the ica Operon Involved in Biofilm Formation

“…Such GW repeats, also found in the staphylococcal autolysins LytA (54), Atl (39), AtlE (18), Aas (20), and AtlC (this study), may serve for cell surface anchoring in staphylococci as they do in L. monocytogenes. Synthetic 10-to 30-mer oligopeptides derived from repeat 1 of Atl were synthesized, and their effects on the autolysis of S. aureus cells were studied (50). All active peptides were located on the C-terminal side of repeat 1 and are suspected to affect the interaction between the autolytic enzymes and lipoteichoic acid.…”

The autolytic activity of the recombinant amidase ofStaphylococcus saprophyticusis inhibited by its own recombinant GW repeats

“…GW repeats or fragments of them may play a role as antimicrobial agents. Takano et al [20] used synthetic peptides derived from the GW repeats of the Atl of S. aureus to show that they have equivocal effects on cell suspensions of S. aureus . Some of the peptides led to a rapid decrease of viable cell counts of S. aureus cells.…”