Glycan complexity dictates microbial resource allocation in the large

We present a series of databanks

ABSTRACT: CXCL12 binds to CXCR4, promoting both chemotaxis of lymphocytes and metastasis of cancer cells. We previously identified small molecule ligands that bind CXCL12 and block CXCR4-mediated chemotaxis. We now report a 1.9 Å resolution X-ray structure of CXCL12 bound by such a molecule at a site normally bound by sY21 of CXCR4. The complex structure reveals binding hot spots for future inhibitor design and suggests a new approach to targeting CXCL12−CXCR4 signaling in drug discovery. Chemokines are small but potent chemotactic cytokines (8−14 kDa). To date, about 50 chemokines have been identified and divided into four distinct families (C, CC, CXC, and CX3C) based on the arrangement of conserved cysteines in the N-

The structure of the human gut microbiota is controlled primarily through the degradation of complex dietary carbohydrates, but the extent to which carbohydrate breakdown products are shared between members of the microbiota is unclear. We show here, using xylan as a model, that sharing the breakdown products of complex carbohydrates by key members of the microbiota, such as Bacteroides ovatus, is dependent on the complexity of the target glycan. Characterization of the extensive xylan degrading apparatus expressed by B. ovatus reveals that the breakdown of the polysaccharide by the human gut microbiota is significantly more complex than previous models suggested, which were based on the deconstruction of xylans containing limited monosaccharide side chains. Our report presents a highly complex and dynamic xylan degrading apparatus that is fine-tuned to recognize the different forms of