Stationary phase and nutrient levels trigger transcription of a genomic locus containing a novel peptide (TM1316) in the hyperthermophilic bacterium Thermotoga maritima

The HicAB System: Characteristics and Biological Roles of an Underappreciated Toxin-Antitoxin System

Small genetic elements known as toxin-antitoxin (TA) systems are abundant in bacterial genomes and involved in stress response, phage inhibition, mobile genetic elements maintenance and biofilm formation. Type II TA systems are the most abundant and diverse, and they are organized as bicistronic operons that code for proteins (toxin and antitoxin) able to interact through a nontoxic complex. However, HicAB is one of the type II TA systems that remains understudied. Here, we review the current knowledge of HicAB systems in different bacteria, their main characteristics and the existing evidence to associate them with some biological roles, are described. The accumulative evidence reviewed here, though modest, underscores that HicAB systems are underexplored TA systems with significant potential for future research.

Enabling Ethanologenesis in Moorella thermoacetica through Construction of a Replicating Shuttle Vector

Replicating plasmid shuttle vectors are key tools for efficient genetic and metabolic engineering applications, allowing the development of sustainable bioprocesses using non-model organisms with unique metabolic capabilities. To date, very limited genetic manipulation has been achieved in the thermophilic acetogen, Moorella thermoacetica, partly due to the lack of suitable shuttle vectors. However, M. thermoacetica has considerable potential as an industrial chassis organism, which can only be unlocked if reliable and effective genetic tools are in place. This study reports the construction of a replicating shuttle vector for M. thermoacetica through the identification and implementation of a compatible Gram-positive replicon to allow plasmid maintenance within the host. Although characterisation of plasmid behaviour proved difficult, the designed shuttle vector was subsequently applied for ethanologenesis, i.e., ethanol production in this organism. The non-native ethanologenesis in M. thermoacetica was achieved via plasmid-borne overexpression of the native aldh gene and heterologous expression of Clostridium autoethanogenum adhE1 gene. This result demonstrates the importance of the developed replicating plasmid vector for genetic and metabolic engineering efforts in industrially important M. thermoacetica.