Structural data are available in the RCSB PDB database under the PDB ID 5ZFQ (PilT-4), 5ZFR (PilB).

The growing emergence of antibiotic-resistant bacteria has led to the exploration of naturally occurring defense peptides as antimicrobials. In this study, we found that laterosporulin (LS), a class IId bacteriocin, effectively kills active and nonmultiplying cells of both Gram-positive and Gram-negative bacteria. Fluorescence and electron microscopy suggest that growth inhibition occurs because of increased membrane permeability. The crystal structure of LS at 2.0A resolution reveals an all-b conformation of this peptide, with four b-strands forming a twisted b-sheet. All six intrinsic cysteines are intramolecularly disulfide-bonded, with two disulfides constraining the N terminus of the peptide and the third disulfide crosslinking the extreme C terminus, resulting in the formation of a closed structure. The significance of disulfides in maintaining the in-solution peptide structure was confirmed by CD and fluorescence analyses. Despite a low overall sequence similarity, LS has disulfide connectivity [C I -C V , C II -C IV, and C III -C VI ] like that of b-defensins and a striking architectural similarity with a-defensins. Therefore LS presents a missing link between bacteriocins and mammalian defensins, and is also a potential antimicrobial lead, in particular against nonmultiplying bacteria. DatabaseThe atomic coordinates and the structure factors have been deposited in the Protein Data Bank under accession number 4OZK

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Human SIRT7 is an NAD(+) dependent deacetylase, which belongs to sirtuin family of proteins. SIRT7, like other sirtuins has conserved catalytic domain and is flanked by N- and C-terminal domains reported to play vital functional roles. Here, we report the crystal structure of the N-terminal domain of human SIRT7 (SIRT7(NTD) ) at 2.3 Å resolution as MBP-SIRT7(NTD) fusion protein. SIRT7(NTD) adopts three-helical domain architecture and comparative structural analyses suggest similarities to some DNA binding motifs and transcription regulators. We also report here the importance of N- and C-terminal domains in soluble expression of SIRT7. Proteins 2016; 84:1558-1563. © 2016 Wiley Periodicals, Inc.

In the present study, the reduction kinetics of prefabricated iron ore-graphite/coal composite pellets of different shapes has been studied in a rotary hearth furnace (RHF). Commercial processes involving the RHF such as ITmk3/FASTMET have major problems of low productivity owing to significant heat and mass transfer resistance through the multilayer bed and consequently limited pellet layers over the hearth. In the present investigation, an attempt has been made to improve the heat and mass transfer in such system by increasing the specific surface area of individual pellets. Both the iron ore-graphite and iron ore-coal composite pellets have been reduced in an RHF at a maximum temperature of 1200uC. The ore-coal composite showed much higher degree of reduction (81%) over ore-graphite composite pellets (61%). The tablet shaped pellet with the highest specific surface area displayed a higher degree of reduction than the cylinder or sphere shaped pellets. Although no physical slag metal separation was visible, X-ray diffraction and SEM/EDX of reduced particles indicated separation at the microlevel. Higher amount of reduction and liquid silicate formation for tablet shaped pellets, in comparison with spherical and cylindrical shaped pellets, lay the foundation of a novel process flow scheme involving the use of prefabricated pellets in the RHF.

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Microbial glycan degradation is essential to global carbon cycling. The marine bacterium Salegentibacter sp. Hel_I_6 (Bacteroidota) isolated from seawater off Helgoland island (North Sea) contains an α-mannan inducible gene cluster with a GH76 family endo-α-1,6-mannanase (ShGH76). This cluster is related to genetic loci employed by human gut bacteria to digest fungal α-mannan. Metagenomes from the Hel_I_6 isolation site revealed increasing GH76 gene frequencies in free-living bacteria during microalgae blooms, suggesting degradation of α-1,6-mannans from fungi. Recombinant ShGH76 protein activity assays with yeast α-mannan and synthetic oligomannans showed endo-α-1,6-mannanase activity. Resolved structures of apo-ShGH76 (2.0 Å) and of mutants co-crystalized with fungal mannan-mimicking α-1,6-mannotetrose (1.90 Å) and α-1,6-mannotriose (1.47 Å) retained the canonical (α/α)6 fold, despite low identities with sequences of known GH76 structures (GH76s from gut bacteria: <27%). The apo-form active site differed from those known from gut bacteria, and co-crystallizations revealed a kinked oligomannan conformation. Co-crystallizations also revealed precise molecular-scale interactions of ShGH76 with fungal mannan-mimicking oligomannans, indicating adaptation to this particular type of substrate. Our data hence suggest presence of yet unknown fungal α-1,6-mannans in marine ecosystems, in particular during microalgal blooms.

The disposal and degradation of xenobiotic compounds have been serious issues due to their recalcitrant properties. Microbial oxygenases are the fundamental enzymes involved in biodegradation that oxidize the substrate by transferring oxygen from molecular oxygen. Among oxygenases, catechol dioxygenases are more versatile in biodegradation and are well studied among the bacterial world. The use of catechol dioxygenases in the field is currently not practical due to their aerobically unstable nature. The significance of our research lies in the discovery of aerobically stable and halotolerant catechol dioxygenases that are efficient in degrading the targeted environmental pollutants and, hence, could be used as cost-effective alternatives for the treatment of hypersaline industrial effluents. Moreover, the structural determination of novel catechol dioxygenases would greatly enhance our knowledge of the function of these enzymes and facilitate directed evolution to further enhance or engineer desired properties.