Characterization of the extracellular lipase of Bacillus subtilis and its relationship to a membrane-bound lipase found in a mutant strain

Bacillus subtilis CMK33 is a mutant that is more osmotically fragile than the wild type when it is converted to the protoplast form. The protoplasts of this mutant contain a membrane-bound lipase, which is not found in protoplasts of the wild type. Hydrolysis of the membrane lipid of mutant protoplasts by the lipase is the cause of their fragility. A protein found in the wild type organism specifically inhibits the lipase (Kent, C., and Lennarz, W. J. (1972) Proc. Natl. Acad. Sci. U. S. A. 69, 2793-2797). This paper reports that cultures of both mutant and wild type cells contain an extracellular lipase which accumulates during the logarithmic phase of growth. The extracellular activity appears to be induced by a component of the growth medium. The membrane-bound lipase of the mutant has been partially purified and its properties have been compared to those of the extracellular lipase of the wild type. Their properties and sensitivity to the wild type inhibitor are similar, which suggests that the two molecules are closely related. The subcellular location of the lipase in the mutant has been investigated and compared to the location of the membrane-bound portion of the lipase inhibitor in the wild type. The lipase is located almost exclusively in the cytoplasmic membrane and not in mesosomal vesicles. In contrast, the lipase inhibitor is located in both types of membranes and is more concentrated in mesosomal vesicles. Under appropriate conditions, the appearance of new extracellular lipase activity in mutant cultures is paralleled by the loss of an equivalent amount of lipase activity from protoplasts prepared from the cells. This suggests that the membrane-bound lipase may be an intermediate in the secretion of the extracellular lipase. Because of the mutation in B. subtilis CMK33, which results in the absence of the lipase inhibitor, this intermediate can be found in protoplasts of the mutant, although it is not detectable in the wild type. Consequently, the mutant may be useful in studies of the mechanism of secretion of exoenzymes by Bacilli

Environmental policy and the role of the university

This report focuses on the realm of environmental policy under a state\u27s jurisdiction and addreses ways in which universities can best support a state\u27s formulation of environmental policy. Making policy involves bringing forward an issue for a decision, issuing laws, rules, regulations or decision about specific matters, and evaluating and adjusting the policy after its enactment. Environmental policy is foremost within the jurisdiction of state and local governments, although governance over certain resources has been assumed by the federal government. This is due to three factors. Federal environmental governance relies upon the state and local governments to further define the grand federal policy. Much of environmental policy is based upon land-use, traditionally a premier concern of state and local governments. And finally, matters of local ecology stay within view of local constituents who keep tho e issues on their state representatives\u27 agenda

Search of extended or delayed TeV emission from GRBs with HAWC

Gamma-ray bursts (GRBs) are among the most luminous sources in the universe and the nature of their emission up to very high energy is one of the most important open issue connected with the study of these peculiar events. The High Altitude Water Cherenkov (HAWC) gamma-ray observatory, installed at an altitude of 4100 m a. s. l. in the state of Puebla (Mexico), has completed its second year of full operations. Thanks to its instantaneous field of view of ~2 sr and its high duty cycle ($\ge$ 95%), HAWC is an ideal instrument for the study of transient phenomena such as GRBs. We performed a search for TeV emission delayed with respect to, and of longer duration than the prompt emission observed by satellites. We present here the results obtained by observing at the position of a sample of GRBs detected by the Fermi and Swift satellites from December 2014 to February 2017. The upper limits resulting from this analysis are presented and theoretical implications are discussed.Comment: Presented at the 35th International Cosmic Ray Conference (ICRC2017), Bexco, Busan, Korea. See arXiv:1708.02572 for all HAWC contribution

A Study of Transient Very-High-Energy Gamma-Ray Emission from Gamma-Ray Bursts and Supernovae with H.E.S.S.

Gamma-ray bursts (GRBs) and supernovae (SNe) are well known examples of celestial transient events. Their tremendous energy release provides the ability to accelerate particles to the highest energies. The High Energy Stereoscopic System (H.E.S.S.) is an array of four imaging atmospheric Cherenkov telescopes, covering gamma-ray energies between 100 GeV and 100 TeV (VHE range). In this work the H.E.S.S. data on GRBs are searched for VHE gamma-ray emission. Amongst them is the analysis of GRB 100621A, the brightest X-ray source so far detected by the Swift satellite. Measurements at lower energies make it a promising candidate within the sensitivity reach of the H.E.S.S. instrument, however no indication of VHE emission is found. The derived upper limits constrain the existence of additional spectral components and provide important input for understanding the emission process. Furthermore, H.E.S.S. pointing positions are compared to a recently created, unified SN catalogue in order to identify extragalactic SNe accidentally in the field of view during the observation of other targets. The analysis reveals no significant detection, which allows one to constrain possible VHE emission scenarios. This work also includes a technical discussion of the H.E.S.S. telescope pointing accuracy. A new approach, the SingleCCD concept, is discussed and evaluated, which is interesting for the next generation of imaging atmospheric Cherenkov telescopes

Structure of the Oligosaccharyl Transferase Complex at 12 Å Resolution

SummaryOligosaccharyl transferase (OT) catalyzes the transfer of a lipid-linked oligosaccharide to the nascent polypeptide emerging from the translocon. Currently, there is no structural information on the membrane-embedded OT complex, which consists of eight different polypeptide chains. We report a 12 Å resolution cryo-electron microscopy structure of OT from yeast. We mapped the locations of four essential OT subunits through a maltose-binding protein fusion strategy. OT was found to have a large domain in the lumenal side of endoplasmic reticulum where the catalysis occurs. The lumenal domain mainly comprises the catalytic Stt3p, the donor substrate-recognizing Wbp1p, and the acceptor substrate-recognizing Ost1p. A prominent groove was observed between these subunits, and we propose that the nascent polypeptide from the translocon threads through this groove while being scanned by the Ost1p subunit for the presence of the glycosylation sequon