Dissecting structure-function-stability relationships of a thermostable GH5-CBM3 cellulase from Bacillus subtilis 168

Cellulases participate in a number of biological events, such as plant cell wall remodelling, nematode parasitism and microbial carbon uptake. Their ability to depolymerize crystalline cellulose is of great biotechnological interest for environmentally compatible production of fuels from lignocellulosic biomass. However, industrial use of cellulases is somewhat limited by both their low catalytic efficiency and stability. In the present study, we conducted a detailed functional and structural characterization of the thermostable BsCe15A (Bacillus subtilis cellulase 5A), which consists of a GH5 (glycoside hydrolase 5) catalytic domain fused to a CBM3 (family 3 carbohydrate-binding module). NMR structural analysis revealed that the Bacillus CBM3 represents a new subfamily, which lacks the classical calcium-binding motif, and variations in NMR frequencies in the presence of cellopentaose showed the importance of polar residues in the carbohydrate interaction. Together with the catalytic domain, the CBM3 forms a large planar surface for cellulose recognition, which conducts the substrate in a proper conformation to the active site and increases enzymatic efficiency. Notably, the manganese ion was demonstrated to have a hyper-stabilizing effect on BsCel5A, and by using deletion constructs and X-ray crystallography we determined that this effect maps to a negatively charged motif located at the opposite face of the catalytic site.

A new species of spider fly in the genus Sabroskya Schlinger from Malawi, with a key to Acrocerinae world genera (Diptera, Acroceridae)

In this paper we diagnose the genus Sabroskya Schlinger, 1960 and describe Sabroskya schlingeri sp. n. from Malawi. We also provide dichotomous keys to species of Sabroskya and to world genera of the subfamily Acrocerinae, both extant and extinct.

Revision of Nanophareus, a mysterious harvestman genus from Chile, with descriptions of three new species (Opiliones: Laniatores: Gonyleptidae)

The Chilean genus Nanophareus Roewer, 1929 is revised and three new species are described: N. araucanus sp. nov. (type locality: Parque Nacional La Campana, Valparaiso, Chile); N. bipartitus sp. nov. (type locality: Parque Nacional La Campana, Valparaiso, Chile); N. bosqenublado sp. nov. (type locality: Parque Nacional Fray Jorge, Coquimbo, Chile). The type species, N. palpalis Roewer, 1929, is redescribed and a lectotype is designated. A cladistic analysis was performed using these three new species plus N. palpalis and 14 more laniatorid species, and a data matrix of 72 characters: Seven from the ocularium, 22 from the dorsal scutum, one from the venter, one from the chelicera, eight from the pedipalp, 24 from male legs, and nine from male genitalia. Two equally most parsimonious trees were found (L = 210; C.I. = 0.41; R.I. = 0.51). Nanophareus was recovered as nested within a paraphyletic subfamily Pachylinae. The genus Nanophareus was found to be monophyletic based on the following exclusive synapomorphies: An external row of enlarged tubercles inserted among small ones on lateral margin of the dorsal scutum (innapplicable in N. bosqenublado); the ventro-basal margin of pedipalpal tibia curved 90 degrees in lateral view; and retrolateral seta of the pedipalpal tibia with a socket apically bifid (socket and seta longer than pedipalpal tibia length).

Descriptions of Thereza murutinga sp. nov. and Pristocnemis caipira sp. nov., and new records of Caelopyginae (Opiliones: Laniatores: Gonyleptidae)

Two new species of Caelopyginae are described: Pristocnemis caipira sp. nov. from Parque Nacional da Serra da Canastra, Minas Gerais, Brazil, and Thereza murutinga sp. nov., from Parati, Rio de Janeiro, Brazil. Pristocnemis caipira sp. nov. is diagnosed by shallow grooves on the dorsal scutum, a lower number of tarsal segments, presence of a spine on the anal operculum, large, pointed tubercles on the lateral margins of the dorsal scutum, and an absence of white patches on the dorsal scutum. Thereza murutinga sp. nov. is diagnosed by the combination of the following characters: incomplete median longitudinal groove on area III and absent on area II, prosoma much smaller than opisthosoma, and a large white patch covering the prosoma and whole areas of the opisthosomal scutum. A cladistic analysis including the two new species was performed to investigate their relationship within the subfamily. We obtained 927 trees of 185 steps (CI=0.4, RI=0.74), which corroborated the generic assignments of the new species, but infrageneric relationships remained unsolved. In addition, male genitalia of Ampheres luteus (Giltay) and genera Pristocnemis and Thereza are redescribed, new distribution records for Caelopyginae species are presented, and biogeographical implications are discussed.