Creatine kinase is a bacteriostatic factor with a lectin-like activity

Prior research has shown that creatine kinase (CK) functions as an acute phase reactant in the amphioxus Branchiostoma belcheri. However, the immune and functional roles of CK remain poorly understood. While CK is known to catalyze ATP synthesis from ADP, its involvement in host defense has not been clearly established. No prior work had resolved whether CK contributes to antimicrobial activity. Existing knowledge suggests CK is primarily metabolic, but this paper introduces a new functional dimension. The gap motivated investigation into CK's potential immune roles. This paper explores whether CK can inhibit bacterial growth. The study addresses a key uncertainty about CK's involvement in innate immunity.

The aim of this study was to investigate the immune functions of creatine kinase (CK) in Branchiostoma belcheri. The researchers sought to determine if CK could inhibit bacterial growth after immune stimulation. They also aimed to assess CK's specificity against different bacterial types. The motivation stemmed from the lack of immune characterization for CK. The study focused on whether CK could bind and inhibit Gram-negative bacteria. The researchers tested CK's activity against Escherichia coli and Staphylococcus aureus. They also examined if CK's activity was sugar-sensitive. The study aimed to clarify CK's role in host defense mechanisms.

The researchers used recombinant BbCK produced from the B. belcheri gene. They induced gene expression in response to LPS challenge. Bacterial growth inhibition was tested using E. coli and S. aureus. CK's binding to bacteria was analyzed using binding assays. The effect of various sugars on CK activity was assessed. The team used N-acetyl-d-mannosamine and other sugars to test CK's lectin-like activity. They measured bacterial growth inhibition quantitatively. The study compared responses to Gram-negative and Gram-positive bacteria.

BbCK expression was inducible by LPS challenge in B. belcheri. Recombinant BbCK bound to Escherichia coli and inhibited its growth. BbCK's bacteriostatic activity was suppressed by several sugars. N-acetyl-d-mannosamine and d-glucose reduced CK's inhibitory effect. The activity was specific to Gram-negative bacteria like E. coli. BbCK had little effect on Gram-positive Staphylococcus aureus. The sugar sensitivity suggests lectin-like activity. These findings indicate CK's role in recognizing and inhibiting Gram-negative bacteria.

The authors suggest that CK functions as a bacteriostatic factor in B. belcheri. The findings propose that CK has lectin-like activity against Gram-negative bacteria. The sugar sensitivity supports CK's role in bacterial recognition. The study implies CK contributes to innate immunity in amphioxus. The results suggest CK's activity is specific to Gram-negative bacteria. The data indicate CK's pleiotropic effects include immune recognition. The authors propose CK's role in immune defense is newly characterized. These findings suggest CK's function extends beyond metabolic roles.