Co-fermentation of xylose and cellobiose by an engineered Saccharomyces cerevisiae.

We have integrated and coordinately expressed in Saccharomyces cerevisiae a xylose isomerase and cellobiose phosphorylase from Ruminococcus flavefaciens that enables fermentation of glucose, xylose, and cellobiose under completely anaerobic conditions. The native xylose isomerase was active in cell-free extracts from yeast transformants containing a single integrated copy of the gene. We improved the activity of the enzyme and its affinity for xylose by modifications to the 5'-end of the gene, site-directed mutagenesis, and codon optimization.

The myosin-binding UCS domain but not the Hsp90-binding TPR domain of the UNC-45 chaperone is essential for function in Caenorhabditis elegans.

The UNC-45 family of molecular chaperones is expressed in metazoan organisms from Caenorhabditis elegans to humans. The UNC-45 protein is essential in C. elegans for early body-wall muscle cell development and A-band assembly.

Role of Rab GTPases in membrane traffic and cell physiology.

Intracellular membrane traffic defines a complex network of pathways that connects many of the membrane-bound organelles of eukaryotic cells. Although each pathway is governed by its own set of factors, they all contain Rab GTPases that serve as master regulators. In this review, we discuss how Rabs can regulate virtually all steps of membrane traffic from the formation of the transport vesicle at the donor membrane to its fusion at the target membrane.

An internal domain of Exo70p is required for actin-independent localization and mediates assembly of specific exocyst components.

The exocyst consists of eight rod-shaped subunits that align in a side-by-side manner to tether secretory vesicles to the plasma membrane in preparation for fusion. Two subunits, Sec3p and Exo70p, localize to exocytic sites by an actin-independent pathway, whereas the other six ride on vesicles along actin cables. Here, we demonstrate that three of the four domains of Exo70p are essential for growth.

The UNC-45 chaperone mediates sarcomere assembly through myosin degradation in Caenorhabditis elegans.

Myosin motors are central to diverse cellular processes in eukaryotes. Homologues of the myosin chaperone UNC-45 have been implicated in the assembly and function of myosin-containing structures in organisms from fungi to humans. In muscle, the assembly of sarcomeric myosin is regulated to produce stable, uniform thick filaments.

The structures of exocyst subunit Exo70p and the Exo84p C-terminal domains reveal a common motif.

The exocyst is a large complex that is required for tethering vesicles at the final stages of the exocytic pathway in all eukaryotes. Here we present the structures of the Exo70p subunit of this complex and of the C-terminal domains of Exo84p, at 2.0-A and 2.

Regulation of the myosin-directed chaperone UNC-45 by a novel E3/E4-multiubiquitylation complex in C. elegans.

The organization of the motor protein myosin into motile cellular structures requires precise temporal and spatial control. Caenorhabditis elegans UNC-45 facilitates this by functioning both as a chaperone and as a Hsp90 cochaperone for myosin during thick filament assembly. Consequently, mutations in C.

The UCS family of myosin chaperones.

The canonical UCS (UNC-45/Cro1/She4p) protein, Caenorhabditis elegans UNC-45, was one of the earliest molecules to be shown genetically to be necessary for sarcomere assembly. Genetic analyses of homologues in several fungal species indicate that the conserved UCS domain functionally interacts with conventional type II and unconventional type V myosins. In C.

Role of the myosin assembly protein UNC-45 as a molecular chaperone for myosin.

The organization of myosin into motile cellular structures requires precise temporal and spatial regulation. Proteins containing a UCS (UNC-45/CRO1/She4p) domain are necessary for the incorporation of myosin into the contractile ring during cytokinesis and into thick filaments during muscle development. We report that the carboxyl-terminal regions of UNC-45 bound and exerted chaperone activity on the myosin head.