LECTURE 10 Secondary Metabolite Gene Clusters

Question 1

The biosynthesis genes for fungal secondary metabolites are located where?

Answer 1

in clusters

Question 2

The size of gene clusters

Answer 2

10 kbp- 70 kbp

Question 3

what is an exception?

Answer 3

two separate gene clusters located on different chromosomes are required for the biosynthesis of the meroterpenoids austinol and dehydroaustinol

Question 4

Most of the clusters contain one or several central biosynthesis genes encoding what?

Answer 4

large multidomain, multimodular enzymes belonging to the PKS or NRPS

Question 5

what do some secondary metabolites require for their biosynthesis

Answer 5

trans-prenyltransferases

Question 6

biosynthesis of ergot alkaloids

Answer 6

requires a tryptophan dimethylallyltransferase that catalyses the prenylation of I- Tryptophan

Question 7

The transcription factors of SM gene clusters are often

Answer 7

zinc finger TFs

Question 8

example of zinc finger TFs

Answer 8

• Cys2His2
• Fungal Zn2Cys6

Question 9

Many of the fungal secondary metabolism gene clusters encode

Answer 9

a single transcription factor

Question 10

two regulatory zinc finger proteins for Aflatoxin gene cluster in A. flavus & A. parasiticus

Answer 10

aflR and aflS

Question 11

Sterigmatocystin gene cluster in

Answer 11

A. nidulans

Question 12

the gliotoxin biosynthesis genes are arranged in a cluster consisting of

Answer 12

13 genes regulated by zinc finger transcription factor GliZ in A. fumigatus

Question 13

Deletion of the GliZ-encoding gene results in

Answer 13

the loss of gliotoxin production

Question 14

OE of the GliZ-encoding gene results in

Answer 14

a substantial increase in the gliotoxin level

Question 15

examples of carcinogenic PKS compounds

Answer 15

AflatoxinandSterigmatocystin

Question 16

β-Lactam antibiotics are produced by

Answer 16

both filamentous fungi and
bacteria, including Gram-negative and Gram-positive microorganisms

Question 17

list the three amino acids Penicillins and cephalosporins are synthesized from

Answer 17

l-α-aminoadipic acid (l-α-AAA), l-cysteine and l-valine

Question 18

These precursors are condensed to

Answer 18

the tripeptide δ-(l-α-aminoadipyl)-l- cysteinyl-d-valine (ACV) catalysed by a single enzyme, ACV synthetase (ACVS).

Question 19

what are ACVS encoded by

Answer 19

a single structural gene designated acvA (pcbAB)

Question 20

what occurs In the second step?

Answer 20

oxidative ring closure of the linear tripeptide leads to formation of a bicyclic ring

Question 21

where and when were Secondary metabolite superclusters First discovered

Answer 21

in A. fumigatus in 2013

Question 22

FTC C is a fungal toxin of the

Answer 22

diketopiperazines family of compounds

Question 23

in mammalian cells, FTC is

Answer 23

tremorgenic and causes cell cycle arrest.

Question 24

Fumitremorgin C is a specific, selective, and potent inhibitor at micromolar concentrations of the

Answer 24

breast cancer resistant protein (BCRP/ABCG2), an ABC transporter associated with chemotherapy resistance.

Question 25

Fumagillin B - Target and Effect

Answer 25

Targets Nosema apis, a single-celled parasite causing Nosema disease in honey bees.

Question 26

Fumagillin B Mode of Action

Answer 26

Acts on the multiplying parasite within the gut.

Question 27

Fumagillin B effectiveness

Answer 27

Not effective against spores; primarily works on the disease-producing parasite multiplication to control the infection.

Question 28

Pseurotin A Mode of Action

Answer 28

Pseurotin A acts as a competitive inhibitor against chitin synthase.
Suppresses IgE production.

Question 29

Tools for Discovery of Cryptic & Orphan Gene Clusters

Answer 29

SMURF: Secondary Metabolite Unique Regions Finder.
antiSMASH
FungiFun

Question 30

Aspergilli Gene Clusters Genome Size

Answer 30

Genome size 30-40 Mbp housing around 50 gene clusters.

Question 31

Dermatophyte Arthroderma benhamiae Gene Clusters Genome Size

Answer 31

Genome size 22 Mbp containing 27 gene clusters.