Involvement of the N-terminus of Bax in its intracellular localization and function

We have investigated the sorting and packaging of secretory proteins into secretory granules by an immunological approach. An mAb against secretogranin I (chromogranin B), a secretory protein costored with various peptide hormones and neuropeptides in secretory granules of many endocrine cells and neurons, was expressed by microinjection of its mRNA into the secretogranin I-producing cell line PC12. An mAb against the G protein of vesicular stomatitis virus--i.e., against an antigen not present in PC12 cells--was expressed as a control. The intracellular localization and the secretion of the antibodies was studied by double-labeling immunofluorescence using the conventional and the confocal microscope, as well as by pulse-chase experiments. The secretogranin I antibody, like the control antibody, was transported along the secretory pathway to the Golgi complex. However, in contrast to the control antibody, which was secreted via the constitutive pathway, the secretogranin I antibody formed an immunocomplex with secretogranin I, was packaged into secretory granules, and was released by regulated exocytosis. Our results show that a constitutive secretory protein, unaltered by genetic engineering, can be diverted to the regulated pathway of secretion by its protein-protein interaction with a regulated secretory protein. The data also provide the basis for immunologically studying the role of luminally exposed protein domains in the biogenesis and function of regulated secretory vesicles.

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The N-Terminus of Collagenase MMP-8 Determines Superactivity and Inhibition: A Relation of Structure and Function Analyzed by Biomolecular Interaction Analysis†

Biochemistry ◽

10.1021/bi982618f ◽

1999 ◽

Vol 38 (22) ◽

pp. 7332-7338 ◽

Cited By ~ 10

Author(s):

Martin Farr ◽

Michael Pieper ◽

Juan Calvete ◽

Harald Tschesche

Keyword(s):

Interaction Analysis ◽

Structure And Function ◽

Biomolecular Interaction ◽

Biomolecular Interaction Analysis ◽

N Terminus ◽

And Function

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The Genotype (A to H) Dependent N-terminal Sequence of HBV Large Surface Protein Affects Viral Replication, Secretion and Infectivity

Frontiers in Microbiology ◽

10.3389/fmicb.2021.687785 ◽

2021 ◽

Vol 12 ◽

Author(s):

Guomin Ou ◽

Lingyuan He ◽

Luwei Wang ◽

Ji Song ◽

Xinyuan Lai ◽

...

Keyword(s):

Type Strain ◽

Surface Protein ◽

Dependent Manner ◽

Terminal Sequence ◽

Hbv Replication ◽

B Virus ◽

N Terminus ◽

And Function ◽

Full Length Genome ◽

Type Strains

Genetic variability has significant impacts on biological characteristics and pathogenicity of hepatitis B virus (HBV), in which the N-terminal sequence of the presurface 1 (preS1) region of HBV large surface protein (LHBs) displays genotype (GT) dependent genetic heterogeneity. However, the influence of this heterogeneity on its biological roles is largely unknown. By analyzing 6560 full-length genome sequences of GTA-GTH downloaded from HBVdb database, the preS1 N-terminal sequences were divided into four representative types, namely C-type (representative of GTA, GTB, and GTC), H-type (GTF and GTH), E-type (GTE and GTG), and D-type (GTD), respectively. We artificially substituted the preS1 N-termini of GTC and GTD plasmids or viral strains with each sequence of the four representative types. The roles of preS1 N-terminus on HBV replication, secretion and infectivity were investigated using HepG2 or HepG2-NTCP cells. In the transfection experiments, the results showed that the extracellular HBsAg levels and HBsAg secretion coefficients in D- and E-type strains were significantly higher than those in C- and H-type strains. D-type strain produced more extracellular HBV DNA than C-type strain. We further observed that D-, H-, and E-type strains increased the levels of intracellular replicative HBV DNAs, comparing with C-type strain. In the infection experiments, the levels of extracellular HBeAg, intracellular HBV total RNA and pgRNA/preC mRNA in D- and E-type strains were markedly higher than C and H-type ones. Our data suggest that the preS1 N-termini affect HBV replication, secretion and infectivity in a genotype dependent manner. The C- and H-type strains prefer to attenuate HBsAg secretion, while the strains of D- and E-type promoted infectivity. The existence and function of the intergenotypic shift of preS1 in naturally occurring recombination requires further investigation, as the data we acquired are mostly related to recombinant preS1 region between N-terminus of preS1 from genotypes A-H and the remaining preS1 portion of GTC or GTD.

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Structure-function analysis of Arabidopsis TOPLESS reveals fundamental conservation of repression mechanisms across eukaryotes

10.1101/2020.03.04.976134 ◽

2020 ◽

Author(s):

Alexander R. Leydon ◽

Wei Wang ◽

Hardik P. Gala ◽

Sabrina Gilmour ◽

Samuel Juarez-Solis ◽

...

Keyword(s):

Saccharomyces Cerevisiae ◽

Function Analysis ◽

Structure And Function ◽

Environmental Cues ◽

Auxin Response ◽

Middle Domain ◽

N Terminus ◽

And Function ◽

The Relationship ◽

Repression Domain

SummaryThe plant corepressor TOPLESS (TPL) is recruited to a large number of loci that are selectively induced in response to developmental or environmental cues, yet the mechanisms by which it inhibits expression in the absence of these stimuli is poorly understood. Previously, we had used the N-terminus of Arabidopsis thaliana TPL to enable repression of a synthetic auxin response circuit in Saccharomyces cerevisiae (yeast). Here, we leveraged the yeast system to interrogate the relationship between TPL structure and function, specifically scanning for repression domains. We identified a potent repression domain in Helix 8 located within the CRA domain, which directly interacted with the Mediator middle domain subunits Med21 and Med10. Interactions between TPL and Mediator were required to fully repress transcription in both yeast and plants. In contrast, we found that multimer formation, a conserved feature of many corepressors, had minimal influence on the repression strength of TPL.

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Membrane binding by CHMP7 coordinates ESCRT-III dependent nuclear envelope reformation

10.1101/049221 ◽

2016 ◽

Cited By ~ 1

Author(s):

Yolanda Olmos ◽

Anna Perdrix ◽

Jeremy G Carlton

Keyword(s):

Nuclear Envelope ◽

Membrane Binding ◽

Point Mutations ◽

Binding Activity ◽

Mitotic Exit ◽

Exit Point ◽

Cellular Functions ◽

Endosomal Sorting ◽

N Terminus ◽

And Function

AbstractAmongst other cellular functions, the Endosomal Sorting Complex Required for Transport-III (ESCRT-III) machinery controls nuclear envelope (NE) reformation during mitotic exit by sealing holes in the reforming NE. ESCRT-III also acts to repair this organelle upon migration-induced rupture. The ESCRT-III component CHMP7 is responsible for recruitment of ESCRT-III to the NE. Here, we show that the N-terminus of CHMP7, comprising tandem Winged Helix (WH)-domains, is a membrane-binding module. This activity allows CHMP7 to bind to the Endoplasmic Reticulum (ER), an organelle continuous with the NE, and provides a platform to direct NE-recruitment of ESCRT-III during mitotic exit. Point mutations that disrupt membrane-binding prevent CHMP7 localising to the ER and its subsequent enrichment at the reforming NE. These mutations prevent both assembly of downstream ESCRT-III components at the reforming NE and proper establishment of post-mitotic nucleo-cytoplasmic compartmentalisation. These data identify a novel membrane-binding activity within an ESCRT-III subunit that is essential for post-mitotic nuclear regeneration.One Sentence SummaryCHMP7’s atypical N-terminus is a membrane-binding module that allows assembly and function of ESCRT-III at the nuclear envelope during mitotic exit.

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