Cellulonodin-2 and Lihuanodin: Lasso Peptides with an Aspartimide Post-Translational Modification

Lasso peptides are a family of ribosomally synthesized and post-translationally modified peptides (RiPPs) defined by their threaded structure. Besides the class-defining isopeptide bond, other post-translational modifications (PTMs) that further tailor lasso peptides have been previously reported. Using genome mining tools, we identified a subset of lasso peptide biosynthetic gene clusters (BGCs) that are colocalized with protein L-isoaspartyl methyltransferase (PIMT) homologs. PIMTs have an important role in protein repair, restoring isoaspartate residues formed from asparagine deamidation to aspartate. Here we report a new function for PIMT enzymes in the post-translational modification of lasso peptides. The PIMTs associated with lasso peptide BGCs first methylate an L-aspartate sidechain found within the ring of the lasso peptide. The methyl ester is then converted into a stable aspartimide moiety, endowing the lasso peptide ring with rigidity relative to its unmodified counterpart. We describe the heterologous expression and structural characterization of two examples of aspartimide-modified lasso peptides from thermophilic Gram-positive bacteria. The lasso peptide cellulonodin-2 is encoded in the genome of actinobacterium Thermobifida cellulosilytica, while lihuanodin is encoded in the genome of firmicute Lihuaxuella thermophila. Additional genome mining revealed PIMT-containing lasso peptide BGCs in 48 organisms. In addition to heterologous expression, we have reconstituted PIMT-mediated aspartimide formation in vitro, showing that lasso peptide-associated PIMTs transfer methyl groups very rapidly as compared to canonical PIMTs. Furthermore, in stark contrast to other characterized lasso peptide PTMs, the methyltransferase functions only on lassoed substrates.

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Reactivity-based screening for citrulline-containing natural products reveals a family of bacterial peptidyl arginine deiminases

10.1101/2020.07.16.207027 ◽

2020 ◽

Author(s):

Lonnie A. Harris ◽

Patricia M. B. Saint-Vincent ◽

Xiaorui Guo ◽

Graham A. Hudson ◽

Douglas A. Mitchell

Keyword(s):

Natural Products ◽

Arginine Deiminase ◽

Post Translational Modification ◽

Genomic Context ◽

Lasso Peptide ◽

Lasso Peptides ◽

C Terminus ◽

A Genome ◽

Modified Peptides ◽

Phylogenetic Profiling

ABSTRACTRibosomally synthesized and post-translationally modified peptides (RiPPs) are a family of natural products defined by a genetically encoded precursor peptide that is tailored by associated biosynthetic enzymes to form the mature product. Lasso peptides are a class of RiPP defined by an isopeptide linkage between the N-terminal amine and an internal Asp/Glu residue with the C-terminus threaded through the macrocycle. This unique lariat topology, which provides considerable stability towards heat and proteases, has stimulated interest in lasso peptides as potential therapeutics. Post-translational modifications beyond the class-defining, threaded macrolactam have been reported, including one example of arginine deimination to yield citrulline. Although a citrulline-containing lasso peptide (i.e., citrulassin) was serendipitously discovered during a genome-guided campaign, the gene(s) responsible for arginine deimination has remained unknown. Herein we describe the use of reactivity-based screening to discriminate bacteria that produce arginine-versus citrulline-bearing citrulassins, culminating in the discovery and characterization of 11 new lasso peptide variants. Phylogenetic profiling identified a distally encoded peptidyl arginine deiminase (PAD) gene ubiquitous to the citrulline-containing variants. Absence of this gene correlated strongly with citrulassin variants only containing arginine (des-citrulassin). Heterologous expression of the PAD in a non-citrulassin producer resulted in the production of the deiminated analog, confirming PAD involvement in arginine deimination. The family of PADs were then bioinformatically surveyed for a deeper understanding of its genomic context and potential role in post-translational modification of RiPPs.

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Identification, Cloning and Heterologous Expression of the Gene Cluster Directing RES-701-3, -4 Lasso Peptides Biosynthesis from a Marine Streptomyces Strain

Marine Drugs ◽

10.3390/md18050238 ◽

2020 ◽

Vol 18 (5) ◽

pp. 238 ◽

Cited By ~ 2

Author(s):

Daniel Oves-Costales ◽

Marina Sánchez-Hidalgo ◽

Jesús Martín ◽

Olga Genilloud

Keyword(s):

Heterologous Expression ◽

Gene Cluster ◽

Fermentation Broth ◽

Genome Mining ◽

Biosynthetic Gene Cluster ◽

Open Reading Frames ◽

Tryptophan Residue ◽

Post Translational Modification ◽

Lasso Peptides ◽

Genes Encoding

RES-701-3 and RES-701-4 are two class II lasso peptides originally identified in the fermentation broth of Streptomyces sp. RE-896, which have been described as selective endothelin type B receptor antagonists. These two lasso peptides only differ in the identity of the C-terminal residue (tryptophan in RES-701-3, 7-hydroxy-tryptophan in RES-701-4), thus raising an intriguing question about the mechanism behind the modification of the tryptophan residue. In this study, we describe the identification of their biosynthetic gene cluster through the genome mining of the marine actinomycete Streptomyces caniferus CA-271066, its cloning and heterologous expression, and show that the seven open reading frames (ORFs) encoded within the gene cluster are sufficient for the biosynthesis of both lasso peptides. We propose that ResE, a protein lacking known putatively conserved domains, is likely to play a key role in the post-translational modification of the C-terminal tryptophan of RES-701-3 that affords RES-701-4. A BLASTP search with the ResE amino acid sequence shows the presence of homologues of this protein in the genomes of eight other Streptomyces strains, which also harbour the genes encoding the RES-701-3, -4 precursor peptide, split-B proteins and ATP-dependent lactam synthetase required for the biosynthesis of these compounds.

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Metabolic engineering of CHO cells to prepare glycoproteins

Emerging Topics in Life Sciences ◽

10.1042/etls20180056 ◽

2018 ◽

Vol 2 (3) ◽

pp. 433-442 ◽

Cited By ~ 1

Author(s):

Qiong Wang ◽

Michael J. Betenbaugh

Keyword(s):

Metabolic Engineering ◽

Cho Cells ◽

Genetic Manipulation ◽

Chinese Hamster ◽

Post Translational Modification ◽

Effector Functions ◽

Recombinant Glycoproteins ◽

Production Platform ◽

Chemical Inhibitors ◽

Amino Acid Mutations

As a complex and common post-translational modification, N-linked glycosylation affects a recombinant glycoprotein's biological activity and efficacy. For example, the α1,6-fucosylation significantly affects antibody-dependent cellular cytotoxicity and α2,6-sialylation is critical for antibody anti-inflammatory activity. Terminal sialylation is important for a glycoprotein's circulatory half-life. Chinese hamster ovary (CHO) cells are currently the predominant recombinant protein production platform, and, in this review, the characteristics of CHO glycosylation are summarized. Moreover, recent and current metabolic engineering strategies for tailoring glycoprotein fucosylation and sialylation in CHO cells, intensely investigated in the past decades, are described. One approach for reducing α1,6-fucosylation is through inhibiting fucosyltransferase (FUT8) expression by knockdown and knockout methods. Another approach to modulate fucosylation is through inhibition of multiple genes in the fucosylation biosynthesis pathway or through chemical inhibitors. To modulate antibody sialylation of the fragment crystallizable region, expressions of sialyltransferase and galactotransferase individually or together with amino acid mutations can affect antibody glycoforms and further influence antibody effector functions. The inhibition of sialidase expression and chemical supplementations are also effective and complementary approaches to improve the sialylation levels on recombinant glycoproteins. The engineering of CHO cells or protein sequence to control glycoforms to produce more homogenous glycans is an emerging topic. For modulating the glycosylation metabolic pathways, the interplay of multiple glyco-gene knockouts and knockins and the combination of multiple approaches, including genetic manipulation, protein engineering and chemical supplementation, are detailed in order to achieve specific glycan profiles on recombinant glycoproteins for superior biological function and effectiveness.

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Dicarbonyl derived post-translational modifications: chemistry bridging biology and aging-related disease

Essays in Biochemistry ◽

10.1042/ebc20190057 ◽

2020 ◽

Vol 64 (1) ◽

pp. 97-110

Author(s):

Christian Sibbersen ◽

Mogens Johannsen

Keyword(s):

Mass Spectrometry ◽

Future Research ◽

Amino Acid Residues ◽

Post Translational Modification ◽

Dicarbonyl Compounds ◽

Protein Targets ◽

Post Translational Modifications ◽

Reactive Protein ◽

Glycation End Products ◽

Direct Mass Spectrometry

Abstract In living systems, nucleophilic amino acid residues are prone to non-enzymatic post-translational modification by electrophiles. α-Dicarbonyl compounds are a special type of electrophiles that can react irreversibly with lysine, arginine, and cysteine residues via complex mechanisms to form post-translational modifications known as advanced glycation end-products (AGEs). Glyoxal, methylglyoxal, and 3-deoxyglucosone are the major endogenous dicarbonyls, with methylglyoxal being the most well-studied. There are several routes that lead to the formation of dicarbonyl compounds, most originating from glucose and glucose metabolism, such as the non-enzymatic decomposition of glycolytic intermediates and fructosyl amines. Although dicarbonyls are removed continuously mainly via the glyoxalase system, several conditions lead to an increase in dicarbonyl concentration and thereby AGE formation. AGEs have been implicated in diabetes and aging-related diseases, and for this reason the elucidation of their structure as well as protein targets is of great interest. Though the dicarbonyls and reactive protein side chains are of relatively simple nature, the structures of the adducts as well as their mechanism of formation are not that trivial. Furthermore, detection of sites of modification can be demanding and current best practices rely on either direct mass spectrometry or various methods of enrichment based on antibodies or click chemistry followed by mass spectrometry. Future research into the structure of these adducts and protein targets of dicarbonyl compounds may improve the understanding of how the mechanisms of diabetes and aging-related physiological damage occur.

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Spindle scaling mechanisms

Essays in Biochemistry ◽

10.1042/ebc20190064 ◽

2020 ◽

Vol 64 (2) ◽

pp. 383-396

Author(s):

Lara K. Krüger ◽

Phong T. Tran

Keyword(s):

Cell Size ◽

Spindle Assembly ◽

Dependent Manner ◽

Post Translational Modification ◽

Size Dependent ◽

A Cell ◽

Chromosome Separation ◽

Spindle Elongation ◽

Protein Gradients ◽

Spindle Structure

Abstract The mitotic spindle robustly scales with cell size in a plethora of different organisms. During development and throughout evolution, the spindle adjusts to cell size in metazoans and yeast in order to ensure faithful chromosome separation. Spindle adjustment to cell size occurs by the scaling of spindle length, spindle shape and the velocity of spindle assembly and elongation. Different mechanisms, depending on spindle structure and organism, account for these scaling relationships. The limited availability of critical spindle components, protein gradients, sequestration of spindle components, or post-translational modification and differential expression levels have been implicated in the regulation of spindle length and the spindle assembly/elongation velocity in a cell size-dependent manner. In this review, we will discuss the phenomenon and mechanisms of spindle length, spindle shape and spindle elongation velocity scaling with cell size.

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Molecular Forms of Human Protein C: Comparison and Distribution in Human Adult Plasma

Thrombosis and Haemostasis ◽

10.1055/s-0038-1651025 ◽

1989 ◽

Vol 62 (03) ◽

pp. 902-905 ◽

Cited By ~ 8

Author(s):

Brian S Greffe ◽

Marilyn J Manco-Johnson ◽

Richard A Marlar

Keyword(s):

Heavy Chain ◽

Protein C ◽

Molecular Forms ◽

Post Translational Modification ◽

Single Chain ◽

Beta Form ◽

Sds Page ◽

Dependent Protein ◽

Adult Plasma ◽

The Difference

SummaryProtein C (PC) is a vitamin K-dependent protein which functions as both an anticoagulant and profibrinolytic. It is synthesized as a single chain protein (SC-PC) and post-transla-tionally modified into a two chain form (2C-PC). Two chain PC consists of a light chain (LC) and a heavy chain (HC). The present study was undertaken to determine the composition of the molecular forms of PC in plasma. PC was immunoprecipitated, subjected to SDS-PAGE and Western blotting. The blots were scanned by densitometry to determine the distribution of the various forms. The percentage of SC-PC and 2C-PC was found to be 10% and 90% respectively. This is in agreement with previous work. SC-PC and the heavy chain of 2C-PC consisted of three molecular forms (“alpha”, “beta”, and “gamma”). The “alpha” form of HC is the standard 2C form with a MW of 40 Kd. The “beta” form of HC has also been described and has MW which is 4 Kd less than the “alpha” form. The “gamma” species of the SC and 2C-PC has not been previously described. However, its 3 Kd difference from the “beta” form could be due to modification of the “beta” species or to a separate modification of the alpha-HC. The LC of PC was shown to exist in two forms (termed form 1 and form 2). The difference between these two forms is unknown. The molecular forms of PC are most likely due to a post-translational modification (either loss of a carbohydrate or a peptide) rather than from plasma derived degradation.

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