Question

In a substrate X catabolic gene promoter you replace the normal histones by your experimental histones – ones with arginine side chains in place of histidine. What will be the effect on the concentration of substrate X against the control?

(a) Concentration will increase

(b) Concentration will decrease

(c) Concentration will remain constant

(d) Concentration will fluctuate and no definite result will be obtained

The question was asked in final exam.

My doubt stems from Transcription in Eukaryotes : Chromatin Remodelling in section Gene Expression : Transcription Prokaryotes of Cytogenetics

Answer 1

Right answer is (c) Concentration will remain constant

Explanation: Arginine side chains can’t be acetylated, so there is no regulation. They are always positively charged and never bind loosely so no gene product is produced. As these gene products are catabolic in their absence the substance X is not broken down so its concentration remains constant.