Dataset Information

Characterization of MdpS: An In-depth Analysis of a MUC5B-Degrading Protease from Streptococcus oralis

ABSTRACT: Oral biofilms, comprising hundreds of bacteria and other microorganisms on oral mucosal and dental surfaces, play a central role in oral health and disease dynamics. Streptococcus oralis, a key constituent of these biofilms, contribute significantly to their formation, serving as an early colonizer and microcolony scaffold. The interaction between S. oralis and the orally predominant mucin, MUC5B, is pivotal in biofilm development, yet the mechanism underlying MUC5B degradation remains poorly understood. This study introduces MdpS (Mucin Degrading Protease from Streptococcus oralis), a protease that extensively hydrolyses MUC5B and offers an insight into its sequence homology, physicochemical properties, and substrate- and amino acid specificity. MdpS exhibits high sequence conservation within the species and also explicitly among early biofilm colonizing streptococci. It is characterized as a calcium or magnesium dependent serine protease with strict physicochemical preferences, including narrow pH and temperature tolerance, and high sensitivity to increased sodium chloride and reducing agent concentrations. Furthermore, MdpS primarily hydrolyze proteins with O-glycans, but also show activity towards immunoglobulins IgA1/2 and IgM, suggesting potential immunomodulatory effects. Significantly, MdpS extensively degrades MUC5B in the N- and C-terminal domains, emphasizing its role in mucin degradation with implications in carbon and nitrogen sequestration for S. oralis with a potential function by cross-feeding the oral biofilm. Moreover, the enzyme displays amino acid preferences of serine, threonine or cysteine depending on substrate glycosylation. Understanding the interplay between S. oralis and MUC5B, facilitated by MdpS, has significant implications for the management of a healthy eubiotic oral microenvironment, offering potential targets for interventions aimed at modulating oral biofilm composition and succession. Additionally, the MdpS data challenges the presently acknowledged model of MUC5B degradation, because contrarily MdpS does not necessitate O-glycan removal prior to extensive peptide backbone hydrolysis. These findings emphasize the necessity for further research in this field.

INSTRUMENT(S): impact II, Q Exactive

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Saliva

SUBMITTER: Fredrik Leo

LAB HEAD: Claes Wickström

PROVIDER: PXD046954 | Pride | 2024-02-14

REPOSITORIES: Pride

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Project description:MUC5B is the predominant glycoprotein in saliva and is instrumental in the establishment and maintenance of multi-species eubiotic biofilms in the oral cavity. Investigations of the aciduric Lactobacillaceae family, and its role in biofilms emphasizes the diversity across different genera of the proteolytic systems involved in the nutritional utilization of mucins. We have characterized a cysteine protease from Limosilactobacillus fermentum, MdpL (Mucin degrading protease from Limosilactobacillus) with a high protein backbone similarity with commensals that exploit mucins for attachment and nutrition. MdpL was shown to be associated with the bacterial cell surface, in close proximity to MUC5B, which was sequentially degraded into low molecular weight fragments. Mapping the substrate preference revealed multiple hydrolytic sites of proteins with a high O-glycan occurrence, although hydrolysis was not dependent on the presence of O-glycans. However, since proteolysis of immunoglobulins was absent, and general protease activity was low, a preference for glycoproteins similar to MUC5B in terms of glycosylation and structure is suggested. MdpL preferentially hydrolyzed C-terminally located hydrophobic residues in peptides larger than 20 amino acids, which hinted at a limited sequence preference. To secure proper enzyme folding and optimal conditions for activity, L. fermentum incorporates a complex system that establishes a reducing environment. The importance of overall reducing conditions was confirmed by the activity boosting effect of the added reducing agents L-cysteine and DTT. High activity was retained in low to neutral pH 5.5-7.0, but the enzyme was completely inhibited in the presence of Zn2+. Here we have characterized a highly conserved mucin degrading protease from L. fermentum. MdpL, that together with the recently discovered O-glycanase and O-glycoprotease enzyme groups, increases our understanding of mucin degradation and complex biofilm dynamics.

Project description:Oral biofilms, comprising hundreds of bacteria and other microorganisms on oral mucosal and dental surfaces, play a central role in oral health and disease dynamics. Streptococcus oralis, a key constituent of these biofilms, contribute significantly to their formation, serving as an early colonizer and microcolony scaffold. The interaction between S. oralis and the orally predominant mucin, MUC5B, is pivotal in biofilm development, yet the mechanism underlying MUC5B degradation remains poorly understood. This study introduces MdpS (Mucin Degrading Protease from Streptococcus oralis), a protease that extensively hydrolyses MUC5B and offers an insight into its sequence homology, physicochemical properties, and substrate- and amino acid specificity. MdpS exhibits high sequence conservation within the species and also explicitly among early biofilm colonizing streptococci. It is characterized as a calcium or magnesium dependent serine protease with strict physicochemical preferences, including narrow pH and temperature tolerance, and high sensitivity to increased sodium chloride and reducing agent concentrations. Furthermore, MdpS primarily hydrolyze proteins with O-glycans, but also show activity towards immunoglobulins IgA1/2 and IgM, suggesting potential immunomodulatory effects. Significantly, MdpS extensively degrades MUC5B in the N- and C-terminal domains, emphasizing its role in mucin degradation with implications in carbon and nitrogen sequestration for S. oralis with a potential function by cross-feeding the oral biofilm. Moreover, the enzyme displays amino acid preferences of serine, threonine or cysteine depending on substrate glycosylation. Understanding the interplay between S. oralis and MUC5B, facilitated by MdpS, has significant implications for the management of a healthy eubiotic oral microenvironment, offering potential targets for interventions aimed at modulating oral biofilm composition and succession. Additionally, the MdpS data challenges the presently acknowledged model of MUC5B degradation, because contrarily MdpS does not necessitate O-glycan removal prior to extensive peptide backbone hydrolysis. These findings emphasize the necessity for further research in this field.

Dataset Information

Characterization of MdpS: An In-depth Analysis of a MUC5B-Degrading Protease from Streptococcus oralis

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