Question

To increase the amount of mugineic acid, rice plants were transformed (using Agrobacterium) with a fragment of barley genomic DNA containing two naat genes; naat-A and naat-B, encoding the subunits of the enzyme

• A. S-adenosylmethionine synthetase
• B. Nicotinamine aminotransferase
• C. Nicotinamine synthase
• D. Deoxymugineic acid synthase

Hint:

In molecular biology questions, gene names are often acronyms or abbreviations of the enzyme or protein they encode. Pay close attention to these abbreviations, as they provide a direct clue to the answer (e.g., {naat} for Nicotinamine Aminotransferase).

Answer 1

The Correct Option is B

Step 1: Concept Overview:
The problem focuses on a genetic modification of rice to increase mugineic acid production. Genes {naat-A} and {naat-B} are introduced, and the task is to identify the enzyme they encode.
Step 2: Core Strategy:
The solution hinges on understanding molecular biology nomenclature, where gene names often reflect the enzyme they code for. The gene name {naat} is key. We must determine the enzyme represented by this abbreviation.
Step 3: Detailed Explanation:
Mugineic acid biosynthesis proceeds as follows: \[ \text{Methionine} \rightarrow \text{S-adenosylmethionine (SAM)} \xrightarrow{\text{NAS}} \text{Nicotianamine (NA)} \xrightarrow{\text{NAAT}} \text{3''-deamino-3''-oxonicotianamine} \xrightarrow{\text{DMAS}} \text{Deoxymugineic acid (DMA)} \rightarrow \text{Mugineic acid} \] Key enzymes include:

NAS: Nicotianamine Synthase
NAAT: Nicotianamine Aminotransferase
DMAS: Deoxymugineic Acid Synthase
Given genes {naat-A} and {naat-B}, and knowing {naat} stands for Nicotianamine Aminotransferase, these genes encode subunits of Nicotinamine aminotransferase.
Step 4: Solution:
Genes {naat-A} and {naat-B} encode the enzyme Nicotinamine aminotransferase.