Molecular basis for transposase activation by a dedicated AAA+ ATPase.

Transposases drive chromosomal rearrangements and the dissemination of drug-resistance genes and toxins. Although some transposases act alone, many rely on dedicated AAA+ ATPase subunits that regulate site selectivity and catalytic function through poorly understood mechanisms. Using IS21 as a model transposase system, we show how an ATPase regulator uses nucleotide-controlled assembly and DNA deformation to enable structure-based site selectivity, transposase recruitment, and activation and integration.

Plastic degradation by insect hexamerins: Near-atomic resolution structures of the polyethylene-degrading proteins from the wax worm saliva.

Plastic waste management is a pressing ecological, social, and economic challenge. The saliva of the lepidopteran larvae is capable of oxidizing and depolymerizing polyethylene in hours at room temperature. Here, we analyze by cryo-electron microscopy (cryo-EM) 's saliva directly from the native source.

IS21 family transposase cleaved donor complex traps two right-handed superhelical crossings.

Transposases are ubiquitous enzymes that catalyze DNA rearrangement events with broad impacts on gene expression, genome evolution, and the spread of drug-resistance in bacteria. Here, we use biochemical and structural approaches to define the molecular determinants by which IstA, a transposase present in the widespread IS21 family of mobile elements, catalyzes efficient DNA transposition. Solution studies show that IstA engages the transposon terminal sequences to form a high-molecular weight complex and promote DNA integration.

The crystal structure of human XPG, the xeroderma pigmentosum group G endonuclease, provides insight into nucleotide excision DNA repair.

Nucleotide excision repair (NER) is an essential pathway to remove bulky lesions affecting one strand of DNA. Defects in components of this repair system are at the ground of genetic diseases such as xeroderma pigmentosum (XP) and Cockayne syndrome (CS). The XP complementation group G (XPG) endonuclease cleaves the damaged DNA strand on the 3' side of the lesion coordinated with DNA re-synthesis.

The structure of VgrG1 from Pseudomonas aeruginosa, the needle tip of the bacterial type VI secretion system.

The type VI secretion system (T6SS) is a mechanism that is commonly used by pathogenic bacteria to infect host cells and for survival in competitive environments. This system assembles on a core baseplate and elongates like a phage puncturing device; it is thought to penetrate the target membrane and deliver effectors into the host or competing bacteria. Valine-glycine repeat protein G1 (VgrG1) forms the spike at the tip of the elongating tube formed by haemolysin co-regulated protein 1 (Hcp1); it is structurally similar to the T4 phage (gp27)3-(gp5)3 puncturing complex.

Crystal Structure of Hcp from Acinetobacter baumannii: A Component of the Type VI Secretion System.

The type VI secretion system (T6SS) is a bacterial macromolecular machine widely distributed in Gram-negative bacteria, which transports effector proteins into eukaryotic host cells or other bacteria. Membrane complexes and a central tubular structure, which resembles the tail of contractile bacteriophages, compose the T6SS. One of the proteins forming this tube is the hemolysin co-regulated protein (Hcp), which acts as virulence factor, as transporter of effectors and as a chaperone.

The structure of TAX1BP1 UBZ1+2 provides insight into target specificity and adaptability.

TAX1BP1 is a novel ubiquitin-binding adaptor protein involved in the negative regulation of the NF-kappaB transcription factor, which is a key player in inflammatory responses, immunity and tumorigenesis. TAX1BP1 recruits A20 to the ubiquitinated signaling proteins TRAF6 and RIP1, leading to their A20-mediated deubiquitination and the disruption of IL-1-induced and TNF-induced NF-kappaB signaling, respectively. The two zinc fingers localized at its C-terminus function as novel ubiquitin-binding domains (UBZ, ubiquitin-binding zinc finger).

Human Drg1 is a potassium-dependent GTPase enhanced by Lerepo4.

Human Drg1, a guanine nucleotide binding protein conserved in archaea and eukaryotes, is regulated by Lerepo4. Together they form a complex which interacts with translating ribosomes. Here we have purified and characterized the GTPase activity of Drg1 and three variants, a shortened mutant depleted of the TGS domain, a phosphomimicking mutant and a construct with the two combined mutations.

BRMS151-98 and BRMS151-84 are crystal oligomeric coiled coils with different oligomerization states, which behave as disordered protein fragments in solution.

The breast cancer metastasis suppressor 1 (BRMS1) gene suppresses metastasis without affecting the primary tumor growth. Cellular localization of BRMS1 appears to be important for exerting its effects on metastasis inhibition. We recently described a nucleo-cytoplasmic shuttling for BRMS1 and identified a nuclear export signal within the N-terminal coiled coil.

The structure of BRMS1 nuclear export signal and SNX6 interacting region reveals a hexamer formed by antiparallel coiled coils.

We present here the first structural report derived from breast cancer metastasis suppressor 1 (BRMS1), a member of the metastasis suppressor protein group, which, during recent years, have drawn much attention since they suppress metastasis without affecting the growth of the primary tumor. The relevance of the predicted N-terminal coiled coil on the molecular recognition of some of the BRMS1 partners, on its cellular localization and on the role of BRMS1 biological functions such as transcriptional repression prompted us to characterize its three-dimensional structure by X-ray crystallography. The structure of BRMS1 N-terminal region reveals that residues 51-98 form an antiparallel coiled-coil motif and, also, that it has the capability of homo-oligomerizing in a hexameric conformation by forming a trimer of coiled-coil dimers.

Crystallization and preliminary X-ray diffraction analysis of a breast cancer metastasis suppressor 1 predicted coiled-coil region.

Breast cancer metastasis suppressor 1 (BRMS1) is an inhibitor of metastatic progression and plays a role in several steps of the metastatic cascade. Apart from the ability of BRMS1 to negatively regulate metastasis formation in breast, melanoma and ovarian tumours, very little is known about the molecular aspects of the antimetastatic properties of BRMS1. Here, the expression, purification and crystallization of a functional fragment of human BRMS1 that is predicted to be a coiled-coil region are reported.

Atypical polyproline recognition by the CMS N-terminal Src homology 3 domain.

The CIN85/CMS (human homologs of mouse SH3KBP1/CD2AP) family of endocytic adaptor proteins has the ability to engage multiple effectors and couple cargo trafficking with the cytoskeleton. CIN85 and CMS (Cas ligand with multiple Src homology 3 (SH3) domains) facilitate the formation of large multiprotein complexes required for an efficient internalization of cell surface receptors. It has recently been shown that c-Cbl/Cbl-b could mediate the formation of a ternary complex between one c-Cbl/Cbl-b molecule and two SH3 domains of CIN85, important for the ability of Cbl to promote epidermal growth factor receptor down-regulation.