Lag Phase Is a Dynamic, Organized, Adaptive, and Evolvable Period That Prepares Bacteria for Cell Division.

Lag is a temporary period of nonreplication seen in bacteria that are introduced to new media. Despite latency being described by Müller in 1895, only recently have we gained insights into the cellular processes characterizing lag phase. This review covers literature to date on the transcriptomic, proteomic, metabolomic, physiological, biochemical, and evolutionary features of prokaryotic lag.

A comprehensive catalogue of polyketide synthase gene clusters in lichenizing fungi.

Lichens are fungi that form symbiotic partnerships with algae. Although lichens produce diverse polyketides, difficulties in establishing and maintaining lichen cultures have prohibited detailed studies of their biosynthetic pathways. Creative, albeit non-definitive, methods have been developed to assign function to biosynthetic gene clusters in lieu of techniques such as gene knockout and heterologous expressions that are commonly applied to easily cultivatable organisms.

Lichen ketosynthase domains are not responsible for inoperative polyketide synthases in Ascomycota hosts.

Efforts by lichenologists to characterize lichen polyketide synthases (PKS) through heterologous expression experiments have so far proved unfruitful. A determination of systematic causes of failure is therefore required. Three hypotheses involving the ketosynthase (KS) domain of lichen polyketide synthases (PKS) from Cladonia uncialis are tested: (1) Horizontal versus vertical gene transfer; (2) Typical versus atypical active site residues; (3) Typical versus atypical tertiary protein structure and active site architecture.

Lichen Biosynthetic Gene Clusters Part II: Homology Mapping Suggests a Functional Diversity.

Lichens are renowned for their diverse natural products though little is known of the genetic programming dictating lichen natural product biosynthesis. We sequenced the genome of Cladonia uncialis and profiled its secondary metabolite biosynthetic gene clusters. Through a homology searching approach, we can now propose specific functions for gene products as well as the biosynthetic pathways that are encoded in several of these gene clusters.

Lichen Biosynthetic Gene Clusters. Part I. Genome Sequencing Reveals a Rich Biosynthetic Potential.

Lichens are symbionts of fungi and algae that produce diverse secondary metabolites with useful properties. Little is known of lichen natural product biosynthesis because of the challenges of working with lichenizing fungi. We describe the first attempt to comprehensively profile the genetic secondary metabolome of a lichenizing fungus.

Iron accumulation, glutathione depletion, and lipid peroxidation must occur simultaneously during ferroptosis and are mutually amplifying events.

Ferroptosis is a recently discovered form of regulated necrosis that involves iron-dependent lipid peroxidation. How cells die once ferroptosis is triggered remains unclear. Ferroptosis is hypothesized to require three critical events: (1) accumulation of redox-active iron, (2) glutathione depletion, and (3) lipid peroxidation.

Identification of 6-Hydroxymellein Synthase and Accessory Genes in the Lichen Cladonia uncialis.

A transcribed polyketide synthase (PKS) gene has been identified in the lichen Cladonia uncialis. The complete nucleotide sequence of this PKS was determined from the amplified cDNA, and an assignment of individual domains was accomplished by homology searching using AntiSMASH. A scan of the complete genome sequence of C.

Putative identification of the usnic acid biosynthetic gene cluster by de novo whole-genome sequencing of a lichen-forming fungus.

To identify the biosynthetic gene cluster responsible for the biosynthesis of the polyketide usnic acid we carried out the de novo genome sequencing of the fungal partner of Cladonia uncialis. This was followed by comprehensive in silico annotation of polyketide synthase (PKS) genes. The biosynthesis of usnic acid requires a non-reducing PKS possessing a carbon methylation (CMeT) domain, a terminal Claisen cyclase (CLC) domain, and an accompanying oxidative enzyme that dimerizes methylphloracetophenone to usnic acid.

Limitations of the 'ambush hypothesis' at the single-gene scale: what codon biases are to blame?

Ribosomal frameshifting, a translational error, catastrophically alters the amino acid composition of the nascent protein by shifting the reading frame from the intended contiguous trinucleotide reading. Frameshift events waste energy and resources, and peptide products have unpredictable cytotoxic effects. The 'Ambush Hypothesis' (Seligmann and Pollock 2004, DNA Cell Biol 23:701-5) suggests there is a selective pressure favouring the evolution of out-of-frame ('hidden') stop codons.

Lag phase-associated iron accumulation is likely a microbial counter-strategy to host iron sequestration: role of the ferric uptake regulator (fur).

Iron is an essential metal for almost all forms of life, but potentiates oxidative stress via Fenton catalysis. During microbial lag phase there is a rapid influx of iron with concomitant oxidative hypersensitivity. How and why iron accumulation occurs remains to be elucidated.