Currently there are 9 native Wideangle Zoom lenses for Pentax K-5 and all of these lenses are autofocus (AF) type.
K-5 also has a sensor based image stabilization system which means that all of these lenses will be stabilized when used on K-5.
Since Pentax K-5 has environmental sealings (Weather Sealing), you may like to couple your camera with one of these 2 Wideangle Zoom lenses with Weather Sealings.