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Molecular characterization of a novel lytic enzyme lysc from Clostridium intestinale URNW and its antibacterial activity mediated by positively charged N-terminal extension

DOI: 10.3390/ijms21144894 DOI Help

Authors: Magdalena Plotka (University of Gdansk) , Monika Szadkowska (University of Gdansk) , Maria Håkansson (SARomics Biostructures) , Rebeka Kovačič (SARomics Biostructures) , Salam Al-karadaghi (SARomics Biostructures) , Björn Walse (SARomics Biostructures) , Olesia Werbowy (University of Gdansk) , Anna-karina Kaczorowska (University of Gdansk) , Tadeusz Kaczorowski (University of Gdansk)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: International Journal Of Molecular Sciences , VOL 21

State: Published (Approved)
Published: July 2020
Diamond Proposal Number(s): 20028 , 2119 , 17181

Open Access Open Access

Abstract: Peptidoglycan hydrolytic enzymes are considered to be a promising alternative to conventional antibiotics in combating bacterial infections. To identify novel hydrolytic enzymes, we performed a database search with the sequences of two thermostable endolysins with high bactericidal activity, studied earlier in our laboratory. Both these enzymes originate from Thermus scotoductus bacteriophages MAT2119 and vB_Tsc2631. A lytic enzyme LysC from Clostridium intestinale URNW was found to have the highest amino acid sequence similarity to the bacteriophage proteins and was chosen for further analysis. The recombinant enzyme showed strong activity against its host bacteria C. intestinale, as well as against C. sporogenes, Bacillus cereus, Micrococcus luteus, and Staphylococcus aureus, on average causing a 5.12 ± 0.14 log reduction of viable S. aureus ATCC 25923 cells in a bactericidal assay. Crystallographic studies of the protein showed that the catalytic site of LysC contained a zinc atom coordinated by amino acid residues His50, His147, and Cys155, a feature characteristic for type 2 amidases. Surprisingly, neither of these residues, nor any other of the four conserved residues in the vicinity of the active site, His51, Thr52, Tyr76, and Thr153, were essential to maintain the antibacterial activity of LysC. Therefore, our attention was attracted to the intrinsically disordered and highly positively charged N-terminal region of the enzyme. Potential antibacterial activity of this part of the sequence, predicted by the Antimicrobial Sequence Scanning System, AMPA, was confirmed in our experimental studies; the truncated version of LysC (LysCΔ2–23) completely lacked antibacterial activity. Moreover, a synthetic peptide, which we termed Intestinalin, with a sequence identical to the first thirty amino acids of LysC, displayed substantial anti-staphylococcal activity with IC50 of 6 μg/mL (1.5 μM). This peptide was shown to have α-helical conformation in solution in the presence of detergents which is a common feature of amphipathic α-helical antimicrobial peptides.

Journal Keywords: bacteriophage; endolysin; autolysin; antimicrobial peptide; peptidoglycan; Staphylococcus aureus; thermophiles

Subject Areas: Biology and Bio-materials, Medicine

Instruments: I04-Macromolecular Crystallography