Interrupted adenylation domains are enigmatic fusions, in which one enzyme is inserted into another to form a highly unusual bifunctional enzyme. We present the first crystal structure of an interrupted adenylation domain that reveals a unique embedded methyltransferase. The structure and functional data provide insight into how these enzymes N-methylate amino acid precursors en route to nonribosomal peptides.

Nonribosomal peptides (NRPs) are known sources of therapeutics. Some nonribosomal peptide synthetase assembly lines contain unique functional interrupted adenylation (A) domains, where nature has combined two different functional domains into one bifunctional enzyme. Most often these interrupted A domains contain a part of a methylation (M) domain embedded in their sequence. Herein, we aimed to emulate nature and create fully functional interrupted A domains by inserting two different noncognate M domains, KtzH(M) and TioS(M), into a naturally occurring uninterrupted A domain, Ecm6(AT). We evaluated the engineered enzymes, Ecm6(AMAT) and Ecm6(AMAT), by a series of radiometric assays and found that not only do they maintain A domain activity, but also they gain the site-specific methylation patterns observed in the parent M domain donors. These findings provide an exciting proof-of-concept for generating interrupted A domains as future tools to modify NRPs and increase the diversity and activity of potential therapeutics.

Interrupted adenylation (A) domains contain auxiliary domains within their structure and are a subject of growing interest in the field of nonribosomal peptide biosynthesis. They have been shown to possess intriguing functions and structure as well as promising engineering potential. Here, we present the characterization of an unprecedented type of interrupted A domain from the columbamides biosynthetic pathway, ColG(AM s M b A). This interrupted A domain contains two back-to-back methylation (M) domains within the same interruption site in the A domain, whereas previously, naturally occurring reported and characterized interrupted A domains harbored only one M domain. By a series of radiometric and mass spectrometry assays, we show that the first and second M domains site specifically methylate the side-chain oxygen and backbone nitrogen of L-Ser after the substrate is transferred onto a carrier thiolation domain, ColG(T). This is the first reported characterization of a dimethylating back-to-back interrupted A domain. The insights gained by this work lay the foundation for future combinatorial biosynthesis of site specifically methylated nonribosomal peptides.

The adenylation (A) domains found in nonribosomal peptide synthetases (NRPSs) exhibit tremendous plasticity.

Pulmonary hypertension (PH) has been found to have significant morbidity and mortality. The treatment of PH has advanced considerably with increasingly more effective and safer options. With an increasing effort to diagnose patients early, non-invasive techniques are often used to screen those patients likely to have PH. Computerized tomography (CT) chest scans are increasingly utilized in the evaluation of patients with exertional dyspnea, including those with suspected PH. The main role of the CT scan is to evaluate for any associated underlying diseases. There have been attempts to address the utility of CT to predict the presence of PH. This article reviews previously published investigations to summarize the relationship between pulmonary artery dimensions and PH to determine both the strength of the correlation and its discriminatory ability for use in clinical practice.

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In-depth study of intriguing bacterial interrupted adenylation domains from seven distinct families and six different types.

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