Question 1

Why are so many clusters silent?

Accepted Answer

Because expression depends on signals absent from standard media: nutrient conditions, competitors, host contact and chromatin state all regulate these regions. A cluster present in a genome is best treated as a capability rather than an activity, and demonstrating production requires finding conditions under which it happens.

Question 2

How reliable are cluster predictions from sequence?

Accepted Answer

Boundaries and product class are often predicted well for well-studied families, but the specific structure is not. Prediction tools identify candidates worth pursuing; they do not substitute for isolating the molecule. Describing a predicted product as though it had been observed is a common and avoidable overstatement.

Question 3

When should dereplication happen?

Accepted Answer

Early, before substantial purification effort. Comparing crude extract profiles against databases of known metabolites identifies rediscovery cheaply, whereas finding it out after months of chromatography wastes a large part of a project. Building the check into the routine workflow is worth the setup time.

Question 4

What links a molecule to its cluster?

Accepted Answer

Genetic manipulation: inactivating a core synthase gene and showing the molecule disappears, or expressing the cluster in a host that otherwise lacks it and showing the molecule appears. Correlation between cluster presence and detection across strains is suggestive but does not establish the connection.

Question 5

How much material does structure determination need?

Accepted Answer

More than is usually anticipated. Full structural assignment by spectroscopy needs milligram quantities of pure material, which for a low-yielding pathway may require substantial scale-up. Establishing achievable yield early informs whether structure elucidation is feasible within the project or whether activation work should come first.

Question 6

Is heterologous expression the easier route?

Accepted Answer

Sometimes, and it sidesteps regulation in the native organism, but it introduces its own problems: cluster size, intron handling, precursor availability and post-translational requirements all differ between host and source. Reporting what did not express is as useful to the field as reporting what did.

Question 7

How is bioactivity screening best positioned?

Accepted Answer

As a parallel line rather than the endpoint, since activity in one assay guides prioritisation without defining a molecule. Testing crude extracts can direct fractionation, though activity may be lost on purification if it depends on a mixture, which is worth checking rather than assuming.

Microbiology

Microbiology

Research Frontiers in Fungal Secondary Metabolism and Natural Product Biosynthesis