Biology subjects

Packer, N.

Publications and source records attributed to Packer, N..

3 recordsLinked to original sources

bioRxiv2026

Streptococcus pyogenes transforms the salivary proteome during controlled human infection

Streptococcus pyogenes (Group A Streptococcus, GAS) is among the leading causes of infectious mortality and primarily manifests as acute pharyngitis. The development of an effective vaccine continues to be hindered by an incomplete understanding of the host immune response, particularly in the oropharynx. Here, we provided detailed insights into the dynamic salivary proteome during acute illness in a human clinical trial of controlled infection of 20 healthy adults (CHIVAS-M75 trial). Deep profiling of salivary proteins via mass spectrometry revealed a striking increase in pro-inflammatory plasma proteins such as alpha1-antitrypsin and elements of the complement system during peak infection as a clear indication of the acute phase response in the oral environment. Many of these proteins, such as fibrinogen, are well-defined targets of key streptococcal virulence factors, with others, such as vitronectin, suggested to play a role in the host-pathogen relationship. Several salivary proteins with known antimicrobial properties, such as mucin-7 and cystatin, decreased universally across the infected cohort. For the first time, we have described the local and immediate protein response to acute pharyngitis in the oral cavity, highlighting a general host inflammatory signature and an abundance of GAS virulence targets infiltrating to the site of infection.

molecular biology↗

bioRxiv2026

Immobilised enzyme reactors for post-production glycan modification of purified glycoproteins

Controlling protein glycosylation as a critical quality attribute of biopharmaceuticals remains challenging when glycosylation is coupled to cellular production systems. Here, we present a proof-of-concept glycosyltransferase immobilised enzyme reactor (IMER) housed within a 3D-printed column that enables directed post-production glycan modification of purified glycoproteins. Using {beta}-1,4-galactosyltransferase ({beta}4GalT1-IMER) and -2,6-sialyltransferase (ST6Gal1-IMER) immobilised on Ni-NTA resin, the IMER achieved near-complete galactosylation and substantial sialylation of partially deglycosylated bovine fetuin N-glycans with their respective substrates with a maximum substrate-enzyme contact time of four minutes. Isomeric-level analysis revealed arm-specific addition preferences for both enzymes, consistent with known specificities. The modular IMER design permits sequential connection of individual enzyme chambers, potentially offering a scalable, plug-and-play platform for constructing defined glycan structures on recombinant glycoprotein therapeutics.

molecular biology↗

bioRxiv2024

Remodelling of the glycome of B-cell precursor acute lymphoblastic leukemia cells developing drug-tolerance

Reduced responsiveness of precursor B-acute lymphoblastic leukemia (BCP-ALL) to chemotherapy can be first detected in the form of minimal residual disease leukemia cells that persist after 28 days of initial treatment. The ability of these cells to resist chemotherapy is partly due to the microenvironment of the bone marrow, which promotes leukemia cell growth and provides protection, particularly under these conditions of stress. It is unknown if and how the glycocalyx of such cells is remodelled during the development of tolerance to drug treatment, even though glycosylation is the most abundant cell surface post-translational modification present on the plasma membrane. To investigate this, we performed omics analysis of BCP-ALL cells that survived a 30-day vincristine chemotherapy treatment while in co-culture with bone marrow stromal cells. Proteomics showed decreased levels of some metabolic enzymes. Overall glycocalyx changes included a shift from Core-2 to less complex Core-1 O-glycans, and reduced overall sialylation, with a shift from 2-6 to 2-3 linked Neu5Ac. Interestingly, there was a clear increase in bisecting complex N-glycans with a concomitant increased mRNA expression of MGAT3, the only enzyme known to form bisecting N-glycans. These small but reproducible quantitative differences suggest that individual glycoproteins become differentially glycosylated. Glycoproteomics confirmed glycosite-specific modulation of cell surface and lysosomal proteins in drug-tolerant BCP-ALL cells, including HLA-DRA, CD38, LAMP1 and PPT1. We conclude that drug-tolerant persister leukemia cells that grow under continuous chemotherapy stress have characteristic glycotraits that correlate with and perhaps contribute to their ability to survive and could be tested as neoantigens in drug-resistant leukemia.

cancer biology↗