Table 1.
Site-directed mutations of Cry1Aa, Cry1Ab and Cry1Ac and their influence on toxins’ function against insect pests.
| Toxin | Mutation | Region | Characteristic | Molecular effect | Toxicity | Reference |
|---|---|---|---|---|---|---|
| Cry1Aa | L126C | Helix α4 (domain I) | Reduced capacity to form pores | Low influx of ions | Extremely reduced | [66] |
| R127C | Helix α4 (domain I) | Increased capacity to form pores | Increased influx of ions | Slightly reduced | ||
| M130C | Helix α4 (domain I) | Increased capacity to form pores | Increased influx of ions | Slightly reduced | ||
| R131C | Helix α4 (domain I) | Highly reduced capacity to form pores | Extremely low influx of ions | Extremely reduced | ||
| I132C | Helix α4 (domain I) | Highly reduced capacity to form pores | Extremely low influx of ions | Reduced | ||
| Q133C | Helix α4 (domain I) | Reduced capacity to form pores | Low influx of ions | Extremely reduced | ||
| F134C | Helix α4 (domain I) | Increased capacity to form pores | Increased influx of ions | Reduced | ||
| N135C | Helix α4 (domain I) | Highly reduced capacity to form pores | Extremely low influx of ions | Extremely reduced | ||
| M137C | Helix α4 (domain I) | Increased capacity to form pores | Increased influx of ions | Slightly reduced | ||
| N138C | Helix α4 (domain I) | Highly reduced capacity to form pores | Extremely low influx of ions | Extremely reduced | ||
| S139C | Helix α4 (domain I) | Highly reduced capacity to form pores | Extremely low influx of ions | Reduced | ||
| A140C | Helix α4 (domain I) | Highly reduced capacity to form pores | Extremely low influx of ions | Extremely reduced | ||
| L141C | Helix α4 (domain I) | Increased capacity to form pores | Increased influx of ions | Slightly reduced | ||
| T142C | Helix α4 (domain I) | Highly reduced capacity to form pores | Extremely low influx of ions | Extremely reduced | ||
| A144C | Helix α4 (domain I) | Highly reduced capacity to form pores | Extremely low influx of ions | Extremely reduced | ||
| I145C | Helix α4 (domain I) | Reduced capacity to form pores | Low influx of ions | Slightly reduced | ||
| P146C | Helix α4 (domain I) | Reduced capacity to form pores | Low influx of ions | Extremely reduced | ||
| L147C | Helix α4 (domain I) | Highly reduced capacity to form pores | Extremely low influx of ions | Extremely reduced | ||
| A149C | Helix α4 (domain I) | Increased capacity to form pores | Increased influx of ions | Slightly reduced | ||
| R127E | Helix α4 (domain I) | Increased capacity to form pores | Increased influx of ions | Slightly reduced | [67] | |
| R127N | Helix α4 (domain I) | Increased capacity to form pores | Increased influx of ions | Slightly reduced | ||
| E128C | Helix α4 (domain I) | Highly reduced capacity to form pores | Extremely low influx of ions | Slightly reduced | ||
| E129C | Helix α4 (domain I) | Abolished capacity to form pores | n/a | Extremely reduced | ||
| E129K | Helix α4 (domain I) | Abolished capacity to form pores | n/a | Extremely reduced | ||
| R131D | Helix α4 (domain I) | Increased capacity to form pores | Low influx of ions | Extremely reduced | ||
| R131E | Helix α4 (domain I) | Highly reduced capacity to form pores | Low influx of ions | Slightly reduced | ||
| R131H | Helix α4 (domain I) | Highly reduced capacity to form pores | Low influx of ions | Extremely reduced | ||
| R131Q | Helix α4 (domain I) | Highly reduced capacity to form pores | Extremely low influx of ions | Reduced | ||
| D136C | Helix α4 (domain I) | Highly reduced capacity to form pores | Extremely low influx of ions | Extremely reduced | ||
| D136N | Helix α4 (domain I) | Highly reduced capacity to form pores | Extremely low influx of ions | Extremely reduced | ||
| D136Y | Helix α4 (domain I) | Abolished capacity to form pores | n/a | Extremely reduced | ||
| T142D | Helix α4 (domain I) | Abolished capacity to form pores | n/a | Extremely reduced | ||
| T143D | Helix α4 (domain I) | Abolished capacity to form pores | n/a | Extremely reduced | ||
| Y445C | Loop 3 (domain II) | Reduced Bt-R175 binding capacity | n/a | Extremely reduced | [57] | |
| Cry1Ab | R99E | Helix α3 (domain I) | No oligomer formation | No membrane insertion | Extremely reduced | [68] |
| L100E | Helix α3 (domain I) | No significant alteration | No significant alteration | No significant alteration | ||
| Y107E | Helix α3 (domain I) | No oligomer formation | No membrane insertion | Extremely reduced | ||
| I200D | Helix α6 (domain I) | No significant alteration | No significant alteration | No significant alteration | ||
| Y203D | Helix α6 (domain I) | No significant alteration | No significant alteration | No significant alteration | ||
| R99E | Helix α3 (domain I) | No oligomer formation | No membrane insertion | Reduced | [69] | |
| E129K | Helix α4 (domain I) | Dominant negative effect | Low capacity to insert into cell membrane | Extremely reduced | ||
| N135C | Helix α4 (domain I) | Dominant negative effect | Low capacity to insert into cell membrane | Extremely reduced | ||
| D136N | Helix α4 (domain I) | No competition with wild-type Cry1Ab | Low capacity to insert into cell membrane | Slightly increased | ||
| A140K | Helix α4 (domain I) | No competition with wild-type Cry1Ab | Low capacity to insert into cell membrane | Slightly increased | ||
| T142C | Helix α4 (domain I) | Dominant negative effect | Low capacity to insert into cell membrane | Extremely reduced | ||
| T143D | Helix α4 (domain I) | Dominant negative effect | Low capacity to insert into cell membrane | Extremely reduced | ||
| D136N, T143D | Helix α4 (domain I) | Dominant negative effect | Low capacity to insert into cell membrane | Extremely reduced | ||
| E129K, D136N | Helix α4 (domain I) | Dominant negative effect | Low capacity to insert into cell membrane | Extremely reduced | [71] | |
| G439D | Loop 3 (domain II) | No binding to receptor | Low capacity to insert into cell membrane | No significant alteration | ||
| V171C | Helix α5 (domain I) | Reduced toxin folding | Increased capacity to insert into cell membrane | Highly increased | ||
| L157C | Helix α5 (domain I) | Reduced toxin folding | Increased capacity to insert into cell membrane | Increased | ||
| N372A | Loop 2 (domain II) | Increased biding capacity to BBMVs | n/a | Highly increased | [58] | |
| N372G | Loop 2 (domain II) | Increased biding capacity to BBMVs | n/a | Highly increased | ||
| N372del | Loop 2 (domain II) | Highly reduced binding capacity to BBMVs | n/a | Extremely reduced | ||
| N372A, A282G, L283S | Loop2, Loop α8a, Loop α8 (domain II) | Increased biding capacity to BBMVs | n/a | Highly increased | ||
| Y153D | Loop between α4 and α5 (domain I) | Weaker membrane insertion | n/a | Reduced | [12] | |
| G282A, S283L | 8 Loop (domain II) | Reduced binding to receptor | n/a | Highly reduced | ||
| R345A, Y350A, Y351A | Loop 1 (Domain II) | Reduced binding to receptor | n/a | Slightly reduced | ||
| I373A | Loop 2 (Domain II) | Structure instability | n/a | Reduced | ||
| F371A, G374A | Loop 2 (Domain II) | Alters binding to membrane | Increase in dissociation from the membrane | Highly reduced | ||
| F440A, G439A | Loop 3 (Domain II) | Affects binding to receptor | n/a | Highly reduced | ||
| Cry1Ac | N135Q | Helix α4 (domain I) | No oligomer formation | No membrane insertion | Extremely reduced | [70] |
| Q509A | GalNac binding site (domain III) | Highly reduced binding capacity to APN | n/a | Slightly reduced | [72] | |
| R511A | GalNac binding site (domain III) | Highly reduced binding capacity to APN | n/a | Slightly reduced | ||
| Y513A | GalNac binding site (domain III) | Highly reduced binding capacity to APN | n/a | Slightly reduced | ||
| Q509A | GalNac binding site (domain III) | No significant alteration | n/a | Reduced | [73] | |
| N510A | GalNac binding site (domain III) | Highly reduced binding capacity to ALP | n/a | Reduced | ||
| R511A | GalNac binding site (domain III) | No significant alteration | n/a | Reduced | ||
| Y513A | GalNac binding site (domain III) | Highly reduced binding capacity to ALP | n/a | Extremely reduced | ||
| W545A | GalNac binding site (domain III) | Highly reduced binding capacity to ALP | n/a | Extremely reduced | ||
| T524N | Loop β16-β17 (domain III) | n/a | n/a | Increased | [51] |