1.D.194. The Intestinalin (P30) Peptide Derived from LysC of Clostridium intestinale Strain URNW (Intestinalin) Family The LysC autolysin from Clostridium intestinale URNW (GenBank ERK30183.1) and the peptide Intestinalin (P30) derived from the LysC N-terminal region (aas: KNLLRRIRRKLRNKFSRSDVIKTPKIVEVN), against Staphylococcus aureus ATCC 25923, proved to be effective at a 5 μM concentration while the intact LysC protein was effective at a 4-fold higher concentration (21 μM) (Szadkowska et al. 2022). This peptide is also effective against a wide range of Gram- and Gram+ bacteria. Although positively charged, Intestinalin resides in the membrane and aggregates into small oligomers. Negatively charged phospholipids stabilize peptide oligomers to form water- and ion-permeable pores, disrupting the integrity of bacterial cell membranes. It causes membrane depolarization and affects membrane integrity by forming large pores, resulting in loss of bacterial viability (Szadkowska et al. 2022). Antimicrobial peptides (AMPs) are a class of small peptides that widely exist in nature, and they are an important part of the innate immune system of certain organisms. AMPs have a wide range of inhibitory effects against bacteria, fungi, parasites and viruses, and some of these exert their effects by increasing membrane permeability. These peptides may act via several very different mechanisms (Bahar and Ren 2013) (Huan et al. 2020).
References:
Bahar, A.A. and D. Ren. (2013). Antimicrobial peptides. Pharmaceuticals (Basel) 6: 1543-1575.
Huan, Y., Q. Kong, H. Mou, and H. Yi. (2020). Antimicrobial Peptides: Classification, Design, Application and Research Progress in Multiple Fields. Front Microbiol 11: 582779.
Szadkowska, M., M. Olewniczak, A. Kloska, E. Jankowska, M. Kapusta, B. Rybak, D. Wyrzykowski, W. Zmudzinska, A. Gieldon, A. Kocot, A.K. Kaczorowska, L. Nierzwicki, J. Makowska, T. Kaczorowski, and M. Plotka. (2022). A Novel Cryptic Clostridial Peptide That Kills Bacteria by a Cell Membrane Permeabilization Mechanism. Microbiol Spectr e0165722. [Epub: Ahead of Print]
Examples:
TC#	Name	Organismal Type	Example
1.D.194.1.1	Intestinalin (P30), a 30 aa peptide derived from the first 30 aas of LysC, derived from Clostridium intestinale strain URNW. The GenBank accession # given with this entry corresponds to the entire LysC protein as the 30 aa peptide does not yet have an accession #. The protein is predicted by the WHAT program to have an N-terminal TMS although this region does not show strong hydrophobicity. It forms large pores due to oligomerization of the 30 aa peptide.		Intestinalin of Clostridium intestinale

1.D.194.1.2	Peptidoglycan recognition protein family protein of 150 aa		*PG recognition protein of Bacillus cereus* group**

1.D.194.1.3	N-acetylmuramoyl-L-alanine amidase of 204 aas and 1 N-terminal TM		Amidase of Armatimonadetes bacterium

1.D.194.1.4	Peptidoglycan recognition protein 5		PRP5 of Micropterus dolomieu