An allosteric MALT1 inhibitor is a molecular corrector rescuing function in an immunodeficient patient.

MALT1 paracaspase is central for lymphocyte antigen-dependent responses including NF-κB activation. We discovered nanomolar, selective allosteric inhibitors of MALT1 that bind by displacing the side chain of Trp580, locking the protease in an inactive conformation. Interestingly, we had previously identified a patient homozygous for a MALT1 Trp580-to-serine mutation who suffered from combined immunodeficiency.

Assembly scaffold NifEN: A structural and functional homolog of the nitrogenase catalytic component.

NifEN is a biosynthetic scaffold for the cofactor of Mo-nitrogenase (designated the M-cluster). Previous studies have revealed the sequence and structural homology between NifEN and NifDK, the catalytic component of nitrogenase. However, direct proof for the functional homology between the two proteins has remained elusive.

The paracaspase MALT1 cleaves HOIL1 reducing linear ubiquitination by LUBAC to dampen lymphocyte NF-κB signalling.

Antigen receptor signalling activates the canonical NF-κB pathway via the CARD11/BCL10/MALT1 (CBM) signalosome involving key, yet ill-defined roles for linear ubiquitination. The paracaspase MALT1 cleaves and removes negative checkpoint proteins, amplifying lymphocyte responses in NF-κB activation and in B-cell lymphoma subtypes. To identify new human MALT1 substrates, we compare B cells from the only known living MALT1(mut/mut) patient with healthy MALT1(+/mut) family members using 10-plex Tandem Mass Tag TAILS N-terminal peptide proteomics.

Interlaboratory study on differential analysis of protein glycosylation by mass spectrometry: the ABRF glycoprotein research multi-institutional study 2012.

One of the principal goals of glycoprotein research is to correlate glycan structure and function. Such correlation is necessary in order for one to understand the mechanisms whereby glycoprotein structure elaborates the functions of myriad proteins. The accurate comparison of glycoforms and quantification of glycosites are essential steps in this direction.

Spectroscopic characterization of the isolated iron-molybdenum cofactor (FeMoco) precursor from the protein NifEN.

The FeMoco of Mo-nitrogenase provides the active site for substrate reduction. Previously, a FeMoco precursor was captured on NifEN, a scaffold protein for FeMoco biosynthesis. Here, we report the isolation of FeMoco precursor from NifEN.

Structural models of the [Fe4S4] clusters of homologous nitrogenase Fe proteins.

The iron (Fe) proteins of molybdenum (Mo)-, vanadium (V)-, and iron (Fe)-only nitrogenases are encoded by nifH, vnfH, and anfH, respectively. While the nifH-encoded Fe protein has been extensively studied over recent years, information regarding the properties of the vnfH- and anfH-encoded Fe proteins has remained scarce. Here, we present a combined biochemical, electron paramagnetic resonance (EPR) and X-ray absorption spectroscopy (XAS) analysis of the [Fe(4)S(4)] clusters of NifH, VnfH, and AnfH of Azotobacter vinelandii .

Characterization of isolated nitrogenase FeVco.

The cofactors of the Mo- and V-nitrogenases (i.e., FeMoco and FeVco) are homologous metal centers with distinct catalytic properties.

Formation of a homocitrate-free iron-molybdenum cluster on NifEN: implications for the role of homocitrate in nitrogenase assembly.

Molybdenum (Mo)-dependent nitrogenase is a complex metalloprotein that catalyzes the biological reduction of dinitrogen (N(2)) to ammonia (NH(3)) at the molybdenum-iron cofactor (FeMoco) site of its molybdenum-iron (MoFe) protein component. Here we report the formation of a homocitrate-free, iron-molybdenum ("FeMo") cluster on the biosynthetic scaffold of FeMoco, NifEN. Such a NifEN-associated "FeMo" cluster exhibits EPR features similar to those of the NifEN-associated, fully-complemented "FeMoco", which originate from the presence of Mo in both cluster species; however, "FeMo" cluster and "FeMoco" display different temperature-dependent changes in the line shape and the signal intensity of their respective EPR features, which reflect the impact of homocitrate on the redox properties of these clusters.

Stepwise formation of P-cluster in nitrogenase MoFe protein.

The P-cluster of nitrogenase is one of the most complex biological metallocenters known to date. Despite the recent advances in the chemical synthesis of P-cluster topologs, the biosynthetic mechanism of P-cluster has not been well defined. Here, we present a combined biochemical, electron paramagnetic resonance, and X-ray absorption spectroscopy/extended X-ray absorption fine-structure investigation of the maturation process of P-clusters in DeltanifH molybdenum-iron (MoFe) protein.

Optimization of FeMoco maturation on NifEN.

Mo-nitrogenase catalyzes the reduction of dinitrogen to ammonia at the cofactor (i.e., FeMoco) site of its MoFe protein component.