Volume 8 Issue 9, September 2012

Volume 8 Issue 9

Basement membranes are a specialized extracellular matrix underlying epithelia that are composed of collagen IV networks, which in turn contain sulfilimine bonds between a methionine sulfur and a hydroxylysine nitrogen. Now, peroxidasin is shown to be the enzyme that catalyzes the formation of these unusual bonds via the production of hypohalous acid intermediates. The image shows the collagen network and a knot held together by sulfilimine bonds. Cover art by Erin Dewalt and MaryLou Quillen, based on an image from Joseph T. Roland. Article, p784; News & Views, p740

Research Highlights

News and Views

  • News & Views |

    Type IV collagen, a major constituent of basement membranes, contains an unusual intermolecular sulfilimine crosslink whose route of biosynthesis has remained undefined. An oxidative triad consisting of peroxidasin, H2O2 and halide is now shown to drive sulfilimine generation in vivo.

    • Stephen J Weiss
  • News & Views |

    Glycosyltransferases, enzymes that catalyze glycosidic bond formation, are one of the most important but least well-characterized protein families found in nature. A new label-free, high-throughput glycan array–based strategy enables rapid profiling of tens of thousands of potential glycosyltransferase reactions.

    • Jeffrey C Gildersleeve
  • News & Views |

    Single-molecule observations reveal that lipid- and protein-based interactions jointly contribute to the interactions among glycosylphosphatidylinositol-anchored proteins in membranes. Understanding these interactions will help to refine long-evolving (and still debated) models of 'raft' domains in biological membranes.

    • John R Silvius

Brief Communications

  • Brief Communication |

    Genetic code expansion by ribosomal incorporation of non-natural amino acids has provided a useful approach for site-specific protein modification. This approach has now been extended to the model organism Drosophila melanogaster, permitting the introduction of non-standard amino acids into proteins within specific cell and tissue types and across developmental stages.

    • Ambra Bianco
    • , Fiona M Townsley
    • , Sebastian Greiss
    • , Kathrin Lang
    •  & Jason W Chin

Articles

  • Article |

    AID/APOBEC deaminases, which convert cytosine bases to uracils in DNA and RNA, have recently been assigned a role in epigenetic regulation as components of DNA demethylation pathways. A systematic study shows that AID/APOBEC enzymes preferentially deaminate unmodified cytosine over its C5-modified forms, calling into question the plausibility of deaminase-mediated DNA demethylation pathways.

    • Christopher S Nabel
    • , Huijue Jia
    • , Yu Ye
    • , Li Shen
    • , Hana L Goldschmidt
    • , James T Stivers
    • , Yi Zhang
    •  & Rahul M Kohli
  • Article |

    Application of a new thermal light scattering technique to quantitatively analyze nearly 150 mutants of the rhomboid intramembrane protease GlpG, coupled with thermodynamic measurements and protease assays, reveals how interactions throughout the molecule collaborate to support enzyme structure and function.

    • Rosanna P Baker
    •  & Sinisa Urban
  • Article |

    Discovery of the native activity of the ~60,000 putative glycosyltransferases remains a substantial challenge. A high-throughput, label-free method drastically speeds this process, with assays of 85 enzymes, 24 acceptors and 7 donors returning functions for four new proteins.

    • Lan Ban
    • , Nicholas Pettit
    • , Lei Li
    • , Andreea D Stuparu
    • , Li Cai
    • , Wenlan Chen
    • , Wanyi Guan
    • , Weiqing Han
    • , Peng George Wang
    •  & Milan Mrksich
  • Article |

    Single-molecule imaging reveals that GPI-anchored proteins in the plasma membrane form homodimer rafts via ectodomain protein interactions. Raft-lipid interactions stabilize higher order oligomers, which trigger intracellular signaling upon ligand binding.

    • Kenichi G N Suzuki
    • , Rinshi S Kasai
    • , Koichiro M Hirosawa
    • , Yuri L Nemoto
    • , Munenori Ishibashi
    • , Yoshihiro Miwa
    • , Takahiro K Fujiwara
    •  & Akihiro Kusumi
  • Article |

    A study of three synthetases involved in streptothricin biosynthesis demonstrates roles for two A domains in activating lysine, with one A domain transferring lysine to a carrier T domain and the second directly catalyzing amide bond formation to form a growing lysine oligopeptide.

    • Chitose Maruyama
    • , Junya Toyoda
    • , Yasuo Kato
    • , Miho Izumikawa
    • , Motoki Takagi
    • , Kazuo Shin-ya
    • , Hajime Katano
    • , Takashi Utagawa
    •  & Yoshimitsu Hamano
  • Article |

    The plant hormone auxin affects many aspects of root development, including lateral root branching. A high-throughput screen in Arabidopsis thaliana has led to the identification of naxillin, a non-auxin chemical probe that enhances lateral root branching and has revealed an important role of the root cap in regulating this process.

    • Bert De Rybel
    • , Dominique Audenaert
    • , Wei Xuan
    • , Paul Overvoorde
    • , Lucia C Strader
    • , Stefan Kepinski
    • , Rebecca Hoye
    • , Ronald Brisbois
    • , Boris Parizot
    • , Steffen Vanneste
    • , Xing Liu
    • , Alison Gilday
    • , Ian A Graham
    • , Long Nguyen
    • , Leentje Jansen
    • , Maria Fransiska Njo
    • , Dirk Inzé
    • , Bonnie Bartel
    •  & Tom Beeckman