The plant cell wall serves as a primary barrier against pathogen invasion. The success of a plant pathogen largely depends on its ability to overcome this barrier. During the infection process, plant parasitic nematodes secrete cell wall degrading enzymes (CWDEs) apart from piercing with their stylet, a sharp and hard mouthpart used for successful infection. CWDEs typically consist of cellulases, hemicellulases, and pectinases, which help the nematode to infect and establish the feeding structure or form a cyst. The study of nematode cell wall degrading enzymes not only enhance our understanding of the interaction between nematodes and their host, but also provides information on a novel source of enzymes for their potential use in biomass based biofuel/bioproduct industries. Although there is comprehensive information available on genome wide analysis of CWDEs for bacteria, fungi, termites and plants, but no comprehensive information available for plant pathogenic nematodes. Herein we have performed a genome wide analysis of CWDEs from the genome sequenced phyto pathogenic nematode species and developed a comprehensive publicly available database.
Hyaluronatelyase produced by various microorganisms are capable of degrading hyaluronic acid in connective tissues and initiating the spread of infection by opening an access for the pathogen into host tissues. The present study attempts to determine the distribution of hyaluronatelyase-producing Streptococcus pneumoniae among invasive, non invasive and carriage isolates, and correlate it with the clinical sources, year of isolation, colonial morphology and their serotypes. A total of 100 isolates from various clinical samples were selected and screened for hyaluronatelyase production and presence of the encoding SpnHyl gene. All isolates possessed SpnHyl gene. Ninety-six isolates including 34 carriage isolates were positive for production of hyaluronatelyase. Four hyaluronatelyase-negative isolates were from blood (2 isolates) and sputum (2 isolates). No significant association was detected among hyaluronatelyase production and bacterial characteristics except for colonial morphology (p = 0.040). High percentages of hyaluronatelyase production in these isolates suggest their possible role as human pathogens.
The alginate lyase AlyQ from Persicobacter sp. CCB-QB2 is a three-domained enzyme with a carbohydrate-binding module (CBM) from family 32. The CBM32 domain, AlyQB, binds enzymatically cleaved but not intact alginate. Co-crystallisation of AlyQB with the cleaved alginate reveals that it binds to the 4,5-unsaturated mannuronic acid of the non-reducing end. The binding pocket contains a conserved R248 that interacts with the sugar's carboxyl group, as well as an invariant W303 that stacks against the unsaturated pyranose ring. Targeting specifically the non-reducing end is more efficient than the reducing end since the latter consists of a mixture of mannuronic acid and guluronic acid. AlyQB also seems unable to bind these two saturated sugars as they contain OH groups that will clash with the pocket. Docking analysis of YeCBM32, which binds oligogalacturonic acid, shows that the stacking of the pyranose ring is shifted in order to accommodate the sugar's axial C1-OH, and its R69 is accordingly elevated to bind the sugar's carboxyl group. Unlike AlyQB, YeCBM32's binding pocket is able to accommodate both saturated and unsaturated galacturonic acid.